ISSN 1393 – 6670

N A T I O N A L P A R K S A N D W I L D L I F E S ERVICE

BENTHIC VEGETATION IN IRISH MARL LAKES: MONITORING HABITAT

3140 CONDITION 2011 TO 2018 – APPENDIX III SITE REPORTS

Cilian Roden, Paul Murphy & James Ryan

I R I S H W I L D L I F E M ANUAL S 124

National Parks and Wildlife Service (NPWS) commissions a range of reports from external contractors to provide scientific evidence and advice to assist it in its duties. The Irish Wildlife Manuals series serves as a record of work carried out or commissioned by NPWS, and is one means by which it disseminates scientific information. Others include scientific publications in peer reviewed journals. The views and recommendations presented in this report are not necessarily those of NPWS and should, therefore, not be attributed to NPWS.

Front cover, small photographs from top row: Limestone pavement, Bricklieve Mountains, Co. Sligo, Andy Bleasdale; Meadow Saffron Colchicum autumnale, Lorcan Scott; Garden Tiger Arctia caja, Brian Nelson; Fulmar Fulmarus glacialis, David Tierney; Common Newt Lissotriton vulgaris, Brian Nelson; Scots Pine Pinus sylvestris, Jenni Roche; Raised bog pool, Derrinea Bog, Co. Roscommon, Fernando Fernandez Valverde; Coastal heath, Howth Head, Co. Dublin, Maurice Eakin; A deep water fly trap anemone Phelliactis sp., Yvonne Leahy; Violet Crystalwort Riccia huebeneriana, Robert Thompson

Main photograph: Cooloorta/Travaun Lough in 2018, Cilian Roden

Benthic vegetation in Irish marl lakes: monitoring habitat 3140 condition 2011 to 2018 – APPENDIX III, Site Reports

Cilian Roden, Paul Murphy1 & James Ryan

1Eireco

Citation: Roden, C., Murphy, P. & Ryan, J. (2020) Benthic vegetation in Irish marl lakes: monitoring habitat 3140 condition 2011 to 2018. Appendix III, Site Reports. Irish Wildlife Manuals, No. 124. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage, Ireland.

The NPWS Project Officer for this report was: Áine O Connor; [email protected]

This IWM was edited by Áine O Connor

ISSN 1393 – 6670

Ordnance Survey Ireland Licence No OSI-NMA-014 © Ordnance Survey Ireland Government of Ireland

 An tSeirbhís Páirceanna Náisiúnta agus Fiadhúlra 2020 National Parks and Wildlife Service 2020

An RoinnTithíochta, Rialtais Áitiúil agus Oidhreachta, 90 Sráid an Rí Thuaidh, Baile Átha Cliath 7, D07 N7CV Department of Housing, Local Government and Heritage, 90 North King Street, Dublin 7, D07 N7CV

Contents

Introduction to Appendix III ...... 1 References used in the Site Reports ...... 1 Appendix III Site Reports ...... 3 Aillebrack Lough, 2012 ...... 5 Annaghmore Lough, 2012 ...... 7 Lough Arrow, 2012 ...... 9 Ballyeighter Lough 2012 ...... 11 Ballyeighter 2, 2012 ...... 14 Lough Bane, 2018 ...... 16 Bleach Lough, 2012 ...... 19 Brick Lough, 2012 ...... 21 Lough Bunny, 2011 and 2018 ...... 23 Lough Carra, 2011 and 2018 ...... 27 Cooloorta/ Travaun Lough, 2012 and 2018 ...... 32 Lough Corrib, 2012 ...... 36 Cullaun Lough, 2012 ...... 38 Cullaunyheeda, 2012 ...... 40 Lough Derravarragh, 2012 ...... 42 Lough Ennell, 2012 ...... 44 Errit Lough, 2012 ...... 46 Fahy Lough, 2012 ...... 48 Finn Lough, 2012 ...... 50 Lough George, 2018 ...... 52 Lough Hackett, 2012 ...... 55 Lough Lene, 2012 ...... 57 Lough Mask, 2012 ...... 59 Melmore Lough, 2018 ...... 61 Muckanagh Lough, 2012 and 2018 ...... 64 Lough Owel, 2011 and 2018 ...... 68 Lough Rea, 2012 and 2018 ...... 72 Spring Lough, 2012 ...... 76 Summerhill Lough, 2012 ...... 78 Urlaur Lough, 2012 ...... 79 Walshpool Lough, 2012 ...... 81 White Lough, 2018 ...... 83

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IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Introduction to Appendix III

This file accompanies the main report:

Roden, C., Murphy, P. & Ryan, J. (2020) Benthic vegetation in Irish marl lakes and measuring ecological deterioration. Irish Wildlife Manuals, No. 124. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage, Ireland.

It contains Appendix III, the Site Reports for marl lakes surveyed in 2011, 2012 and 2018.

References used in the Site Reports

Doddy, P. (2019) Cyanobacterial Communities in Langangen, A. (2005) Charophytes collected in Cos Limestone Lakes & Pools in Ireland: Effects of nutrient Clare (H9) and south-east Galway (H15) in 2003. Irish enrichment on community structure, and implications for Naturalists' Journal 28, 151–158. conservation of marl lakes. Unpublished PhD thesis, Praeger, R.L. (1906) On the botany of Lough Carra. The Galway-Mayo Institute of Technology Irish Naturalist 15, 207–214. Doddy, P., Roden, C.M. & Gammell, M.P. (2019a) Reynolds, S.C.P. (2013) Flora of County Limerick. Microbialite crusts in Irish limestone lakes reflect National Botanic Gardens, Glasnevin. lake nutrient status. Biology and Environment: Roden, C.M. (1999) A survey of Irish machair Loughs. Proceedings of the Royal Irish Academy 119 (1), 1–11. Unpublished report submitted to the Heritage Doddy, P., Roden, C.M. & Gammell, M.P. (2019b) Council. Nutrient-pollution degrades microbialites in Lough Roden, C.M. (2000) A study of karstic algae growing in the Carra, an Irish marl lake. Aquatic Microbial Ecology 83, west of Ireland. Unpublished report submitted to the 203–209. heritage Council. Free, G., Little, R., Tierney, D., Donnelly, K. and Coroni, Roden, C.M. (2001) A report on the vegetation and algal R. (2006) A reference-based typology and ecological plankton of base rich nutrient poor lakes in Clare and assessment system for Irish lakes. Preliminary Mayo. Unpublished report submitted to Heritage Investigations. Final Report. Project 2000-FS-1-M1 Council. Ecological Assessment of Lakes Pilot Study to Roden (2004) Report on sub. Littoral vegetation between Establish Monitoring Methodologies EU (WFD). Kilbeg and Knockferry, Lough Corrib Galway. EPA, Wexford. Unpublished report. Groves, J. & Bullock-Webster, G.R. (1920, 1924) The Roden, C. (2008) The effect of excessive water abstraction on British Charophyta. Ray Society, London. the vegetation and conservation status of Lough Bane, Heuff, H. (1984) The vegetation of Irish Lakes. county Meath/ Westmeath. Special Area of Conservation Unpublished report submitted to the Wildlife no 002120. Updated October 2008. Report to Meath Service, Office of Public Works, Dublin. County Council. Hobbs, W., Irvine, K. and Donohue, I. (2005) Using Roden, C. (2009) The effect of excessive water abstraction on sediments to assess the resistance of a calcareous lake the vegetation and conservation status of Lough Bane, to diffuse nutrient loading. Archiv fur̈ Hydrobiologie county Meath/ Westmeath. Results of monitoring 164, 109125. programme. July 2008-July 2009. 2nd Report (October John, D.M, Champ, W.S.T. and Moore, J.A. (1982) The 2009). Report to Meath County Council. changing status of Characeae in four marl lakes in the Roden, C. (2010) The effect of excessive water abstraction on Irish Midlands. Journal of Life Sciences, Royal Dublin the vegetation and conservation status of Lough Bane, Society 4, 47–71. county Meath/ Westmeath. 3rd Report (December 2010). King, J.J. & Champ, W.S.T. (2000) Baseline water quality Report to Meath County Council. investigations on Lough Carra, western Ireland, with Roden, C. & Murphy, P. (2013) A survey of the benthic reference to water chemistry, phytoplankton and macrophytes of three hard-water lakes: Lough aquatic plants. Biology and Environment: Proceedings of Bunny, Lough Carra and Lough Owel. Irish Wildlife the Royal Irish Academy 100B (1), 13–25. Manuals, No. 70. National Parks and Wildlife Service, Krause, W. & King, J.J. (1994) The ecological status of Department of Arts, Heritage and the Gaeltacht, Lough Corrib, Ireland, as indicated by physiographic Ireland. factors, water chemistry and macrophytic flora. Roden, C. & Murphy, P. (2020) Sub littoral vegetation of Vegetatio 110, 149–161. Lough Arrow in 2019. Report to the INTERREG VA

1 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

CANN (Collaborative Action for the Natura Parks and Wildlife Service, Department of Housing, Network) Project. Local Government and Heritage, Ireland. Roden, C., Murphy, P., Ryan, J. & Doddy, P. (2020) Marl Webb, D.A. & Scannell, M.J.P. (1983) Flora of Connemara Lake (Habitat 3140) Survey and Assessment Methods and the Burren. Royal Dublin Society, Dublin and Manual. Irish Wildlife Manuals, No. 125. National Cambridge University Press, Cambridge.

2 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Appendix III Site Reports

This appendix includes site reports for each of the lakes surveyed in 2011, 2012 and 2018. Where a lake was surveyed in more than one year, data are provided for each year. Reports are ordered alphabetically by lake name. Brief notes on cyanobacterial crust (krustenstein) survey are provided. See the Marl Lake (Habitat 3140) Survey and Assessment Methods Manual (Roden et al., 2020) for information on conservation condition assessment. Note that the 2011 and 2018 surveys targeted the most important Irish marl lakes and Special Areas of Conservation designated to protect the habitat and, therefore, were biased towards lakes in better conservation condition. The following is a key to the table provided at the start of each site report:

Name Lake name used in survey Other names used in maps, literature or other sources. Name used by Alternative name(s) Environmental Protection Agency (EPA) is indicated by ‘EPA’ 12-figure grid reference Depth in metres from Grid Reference and 10-figure with grid Depth (m) bathymetric or other maps, square for lake centroid where available County/ies within which EPA WFD lake water body County EPA code lake is situated code Approximate lake surface OSi Discovery Series, 1:50,000 Area (ha) OSi 1:50,000 sheet area in hectares (ha) map sheet Maximum lake surface Source, date-span and, where Maximum length (km) length, estimated using Nutrient data possible, number of samples GIS for water chemistry data Altitude above sea level in Altitude (m) metres from OSi Discovery 6-digit code and name of Series, 1:50,000 SAC Special Area of Conservation Main bedrock type(s) (SAC), where applicable Geology underlying and surrounding the lake basin. Previous survey Surveyor, survey date and/or citation for previous ecological survey Noteworthy species Lists any noteworthy macrophyte records for the lake from previous surveys Year of 1st survey Year of 2nd survey Date of first conservation condition Date of second conservation Snorkel survey date(s) snorkel survey of submerged condition snorkel survey of vegetation submerged vegetation Names of surveyors, including snorkellers and recorder: Cilian Roden (CR), Surveyors Paul Murphy (PM), Jim (James) Ryan (JR) Number of transects Number of transects sampled during the survey Number of relevés Total number of relevés sampled across all transects Secchi depth (m) Secchi depth, where recorded during the survey Substrates Substrates recorded in relevés during the survey Noteworthy species List of any noteworthy macrophyte species recorded during the survey Total number of vegetation zones recorded during the survey, mainly A) Vegetation zones charophyte and cyanobacterial crust zones Maximum depth of colonisation of vegetation, in metres, on each transect B) Euphotic depth (m) surveyed The sum of the cover of charophytes and cyanobacterial crust (krustenstein), C) C&K score divided by total cover on each transect D) Total phosphorus (mg/l) Total phosphorus concentration E) Colour (Hazen units) Water colour F) Index (TP × Colour) The product of total phosphorus in mg/l and water colour in Hazen units CONSERVATION Conservation condition of the lake, assessed as per Roden et al. (2020) CONDITION

3 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

The conservation condition of lakes surveyed in 2018 was assessed using the methods of Roden et al. (2020), which should be consulted for further information on all parameters and targets. Further information on cyanobacterial (cyanophyte) crust parameters is available from Doddy (2019) and Doddy et al. (2019a, b). The following is a simple key to the condition assessment table at the end of each site report for lakes surveyed in 2018:

Parameter Target Note Condition Stable or Area surface area of the lake Good/Poor/Bad increasing The number of distinct charophyte zones Number of vegetation occurring. Includes cyanobacterial crust zone. 4 or more* Good/Poor/Bad zones There should be no loss of zones, where previous data exist The deepest recorded euphotic depth (across transects) is used. For complex, multi-basin lakes, the deepest euphotic depth per basin is Euphotic depth (m) >7 Good/Poor/Bad used, however the overall lake condition is determined by the worst basin rating. See Lough Carra for example. Cover of cyanobacterial crust, or krustenstein, Crust cover (%) >70 Good/Poor/Bad from dedicated shoreline survey Crust chlorophyll a Chlorophyll a concentration in cyanobacterial <45 Good/Poor/Bad (µg/cm3 ±s.e.) crust, or krustenstein The presence/absence of chlorophyte cells Crust chlorophytes expressed as a percentage of the total number of (% frequency, mean <45 Good/Poor/Bad samples (‘fields-of-view’) from microscopic ±s.e.) examination Charophyte and cyanobacterial crust (krustenstein) score – proportion of the total C&K score >0.6 Good/Poor/Bad vegetation cover composed of charophyte and cyanobacterial crust at or above Lake level cyanobacterial Lake water level at time of survey Good/Poor/Bad crust Total phosphorus ≤0.01 Total phosphorus concentration Good/Poor/Bad (TP) (mg/l) Colour (Hazen units) <15 Water colour Good/Poor/Bad The product of total phosphorus in mg/l and Index (TP × Colour) <0.1 Good/Poor/Bad water colour in Hazen units Overall assessment Good/Poor/Bad

4 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Aillebrack Lough, 2012 Name Aillebrack Alternative name(s) Grid Reference 058566243406, L5856643406 Depth (m) County Galway EPA code 31_113 Area (ha) 3.8 ha OSi 1:50,000 sheet 44 Maximum length (km) 0.3 km Nutrient data None available Altitude (m) 10 m 002074, Slyne Head Peninsula Machair sand and SAC Geology SAC metamorphic rock Previous survey Roden (1999) Noteworthy species Potamogeton coloratus, five Chara species 1999 2012 Snorkel survey date(s) 10/08/2012 Surveyors CR CR, PM Number of transects 2 Number of relevés 5 20 Secchi depth (m) Substrates Sand Sand Noteworthy species Potamogeton coloratus A) Vegetation zones B) Euphotic depth (m) 3 3 C) C&K score D) Total phosphorus (mg/l) E) Colour (Hazen units) F) Index (TP × Colour) CONSERVATION GOOD CONDITION

Previous survey

The lake was examined by Roden (1999), he recorded the following species

Charophytes Vascular plants Chara aspera Littorella uniflora Chara contraria Myriophyllum alterniflorum Chara curta Myriophyllum spicatum Chara globularis Potamogeton coloratus Chara rudis Potamogeton gramineus Potamogeton pectinatus

Vegetation grew to about 3 m, the maximum depth of the lake. No threats were noted.

2012 condition assessment

Machair loughs such as Aillebrack or Fahy differ from marl lakes in being very shallow (less than 5 m) with cloudier water and some characteristic plants such as Ranunculus baudottii and Potamogeton pectinatus. Nevertheless, a compressed zonation occurs of Chara aspera and C. curta, in shallow water with intermixed C. rudis and C. globularis /virgata in 1-4 m. The scarcity of angiosperm vegetation is also a feature shared with marl lakes.

The data from Aillebrack were not used in the analysis in the main report, as machair loughs probably differ from marl lakes on limestone. Nevertheless the diverse charophyte flora and scarcity of vascular plants both in 1999 and 2012 show the lake was in Good conservation condition.

5 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Aillebrack Lough showing positions of 2012 transects and relevés with depth.

Aillebrack Lough, 2012; Large Chara rudis at 1.5 m (top) and north shore (bottom).

6 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Annaghmore Lough, 2012 Name Annaghmore Lough Alternative name(s) Grid Reference 189972283651, M8997283651 Depth (m) County Roscommon EPA code 26_669 Area (ha) 53.1 ha OSi 1:50,000 sheet 33 Maximum length (km) 1.6 km Nutrient data EPA Altitude (m) 46 m 001626, Annaghmore Lough SAC (Roscommon) SAC (this SAC Geology Drift over limestone is not selected for habitat 3140) Previous survey EPA WFD Monitoring lake Noteworthy species Six charophyte species and Potamogeton filiformis 2012 Snorkel survey date(s) 01/09/2012 Surveyors CR, PM Number of transects 2 Number of relevés 22 Secchi depth (m) 3.5 m Substrates Marl sand Noteworthy species see above A) Vegetation zones 4 B) Euphotic depth (m) 6 m C) C&K score 0.763 D) Total phosphorus (mg/l) 0.0091 E) Colour (Hazen units) 20 F) Index (TP × Colour) 0.182 CONSERVATION CONDITION GOOD

2012 condition assessment

This lake has two basins with euphotic depths of 6 m. It is surrounded by farm land and fen. Marl is very extensive in shallow water and there is little rock exposed. Cyanobacterial crust is well developed. A typical zonation of crust/C. curta/C. rudis/C. virgata occurs. Angiosperms are largely confined to the C. rudis belt. Both Secchi and euphotic depth are slightly shallow, possibly due to the lake basin being on drift rather than bedrock. However there are no other signs of degradation and the lake’s status is rated Good.

Annaghmore Lough, 2012; Hippuris vulgaris growing on the slope at 1.6 m.

7 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Annaghmore Lough showing positions of 2012 transects and relevés with depth.

Annaghmore Lough, 2012; Schoenoplectus lacustris growing on slope break in western basin.

8 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Arrow, 2012 Name Lough Arrow Alternative name(s) Grid Reference 178991312053, G7899112053 Depth (m) 30 m County Sligo, Roscommon EPA code 35_159 Area (ha) 1,247 ha OSi 1:50,000 sheet 25 & 33 Maximum length (km) 7 km Nutrient data EPA Altitude (m) 53 m SAC 001673, Lough Arrow SAC Geology Drift over limestone Previous survey EPA WFD Monitoring Lake Noteworthy species Aegaropila linnaei; formerly rich in charophyte species (10 species) 2012 2019 (CANN project) Snorkel survey date(s) 01/09/2012 2-3/09/2019 Surveyors CR, PM CR, PM Number of transects 2 10 Number of relevés 14 58 Secchi depth (m) 4.2 m 4 Substrates Muddy silt Mud silt rock Noteworthy species Aegaropila linnaei A) Vegetation zones 1 2 B) Euphotic depth (m) T1: 6.7 m; T2: 3.3 m, 4.2 C) C&K score 0.36 0.37 D) Total phosphorus (mg/l) 0.007 0.012 E) Colour (Hazen units) 22.6 21 F) Index (TP × Colour) 0.24 0.25 CONSERVATION POOR POOR CONDITION

2012 condition assessment

Lough Arrow is a large lake showing many signs of eutrophication. Water transparency is poor with much particulate matter. Secchi and euphotic depths are low. No cyanobacterial crust was encountered and Chara rudis and C. virgata were the only charophytes recorded. Angiosperms, especially Lemna trisulca and Elodea canadensis were common, along with large Potamogeton species.

The Zebra mussel was abundant and the recently introduced Elodea nuttallii was found near station 504.

If it is assumed that Arrow was once a typical limestone lake it must be concluded that it is now in a very degraded state with most of the typical vegetation of marl lakes replaced by “weedy” angiosperm species and Zebra Mussel.

Lough Arrow, 2012; Chara rudis at 1.3 m covered in Cladophora or blanket weed.

9 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Arrow showing positions of 2012 transects and relevés with depth.

Lough Arrow, 2012; looking east. Note extensive reedbeds.

2019 survey and condition assessment for the CANN Project

Roden & Murphy (2020) carried out a survey of the lake on behalf of Sligo Institute of Technology and the INTERREG VA CANN (Collaborative Action for the Natura Network) project in 2019. Their findings were similar to the 2012 results, but some differences were noted. Small patches of cyanobacterial crust, albeit in poor condition, were recorded. A few plants of a third charophyte species, Chara curta, were found, but important metrics such as euphotic depth, charophyte and cyanobacterial crust cover were still low in value. The introduced Elodea nuttallii was widespread. An interesting addition to the flora was the great abundance at the north of the lake of Cladophora balls (Aegaropila linnaei).

They noted that the Inland Fisheries Trust had recorded up to 11 charophyte species in 1984 and that water colour was much lower in the 20th Century (Roden & Murphy, 2020). These changes undoubtedly indicate a grave decline in ecological condition during the last 30 years.

10 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Ballyeighter Lough 2012 Name Ballyeighter Lough 1 Ballyeighter 1, Ballyeighter North, Ballyeighter Lough (northeast). Ballyeighter Lough (1) and Balleighter 2 are both labelled as “Balleighter Lough” on the 6” maps. There are issues with the lake boundaries (shoreline) in this area at 1:50,000 scale, with submerged marl/cyanobacterial crust, Cladium swamp and Alternative name(s) reedbeds all mapped as dry land. This has led to errors in the EPA’s WFD datasets. The original Balleighter Lough, as mapped on 6”, has 3 separate/discrete WFD lake segment polygons. These are part of a single wetland, and segment 27_269 is connected by open water, while 27_270 is connected by reedbed and swamp Grid Reference 135712194040, R3571294040 Depth (m) >7 m County Clare EPA code 27_106, 27_269, 27_270 Area (ha) c. 28 ha OSi 1:50,000 sheet 52 Maximum length (km) 1.8 km Nutrient data Free et al. (2006) Altitude (m) 17 m 001926, East Burren Complex SAC Geology Limestone SAC Previous survey Langangen (2005) (referred to as “North Ballyeighter Lough (by Treanmanagh) Noteworthy species Six species of charophyte 2012 Snorkel survey date(s) 12/07/2012 Surveyors CR, PD Number of transects 2 Number of relevés 18 Secchi depth (m) 4 m Substrates Marl Noteworthy species Juncus bulbosus A) Vegetation zones 4 B) Euphotic depth (m) 6.5 m (south basin), 7.3 m (north basin) C) C&K score 0.904 D) Total phosphorus (mg/l) 0.005 E) Colour (Hazen units) 27 F) Index (TP × Colour) 0.135 CONSERVATION CONDITION GOOD

2012 condition assessment

This lake has two basins with euphotic depths of 7.3 m (north basin) and 6.5 m (south basin). While Secchi depth is intermediate, few angiosperms occur and the Chara rudis zone is partly replaced by C. contraria. The slightly shallow euphotic zone of 6.5 m in the south basin may be due to peat staining of the water. There are no obvious threats to the lake and it is rated as Good. The presence of Juncus bulbosus is very unusual in such an alkaline environment, (but see Webb & Scannell, 1983).

Ballyeighter Lough 1, 2012; Cyanobacterial crust at 1 m.

11 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Ballyeighter Lough 1 (north-east) showing positions of 2012 transects and relevés with depth.

Ballyeighter Lough 1, 2012; northern shore, note reeds growing on slope edge.

12 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Ballyeighter area, showing Ballyeighter Loughs (1 and 2), Lough George, Lough Cullaun and Muckanagh Lough. Purple discs show positions of relevés from the 2012 survey; orange triangles show positions of relevés from the 2018 survey.

13 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Ballyeighter 2, 2012 Name Ballyeighter Lough 2 Ballyeighter Lough (south-west). Ballyeighter Lough and Balleighter 2 are both labelled as ‘Balleighter Lough’ on the 6” maps. There are issues with the lake boundaries (shoreline) in this area at 1:50,000 scale, with submerged marl/cyanobacteral crust, Cladium swamp and Alternative name(s) reedbeds all mapped as dry land. This has led to errors in the EPA’s WFD datasets. Balleighter 2, as mapped on the 6” (as ‘Balleighter Lough’), has 5 separate/discrete WFD lake segment polygons. These are part of a single wetland, and segments 27_303 (‘Lake at Aglish’) and 27_304 are merely two deeper basins within the main lake, whilst the other 3 are connected by reedbed and swamp Grid Reference 133528192434, R3352892434 Depth (m) 27_303, 27_304, 27_302, 27_306, County Clare EPA code 27_301 Area (ha) c. 37 ha OSi 1:50,000 sheet 52 Maximum length (km) 1.5 km Nutrient data None available Altitude (m) 17 m 001926, East Burren Complex SAC Geology Limestone SAC Previous survey C.D. Preston 18/07/1994 Noteworthy species 2012 Snorkel survey date(s) 29/09/2012 Surveyors CR, PD Number of transects 2 Number of relevés 16 Secchi depth (m) 5 m Substrates Marl Noteworthy species Nitella tenuissima A) Vegetation zones 4 B) Euphotic depth (m) T2: 7.9 m; T1: 6.6 m C) C&K score D) Total phosphorus (mg/l) E) Colour (Hazen units) F) Index (TP × Colour) CONSERVATION CONDITION GOOD

2012 condition assessment

This lake surprisingly has no name on the Discovery Series, so is labelled Ballyeighter 2 here. It is a clear water lake with euphotic zone to 7.9 m and Secchi depth to 5 m. Cyanobacterial crust is well developed, Charophyte zones include Chara curta, C. rudis, C. contraria and C. virgata. The rare Nitella tenuissima occurs in shallow water, as does a bryozoan species. No introduced species occur. The lake is an almost text book example of a marl lake in pristine condition and is rated Good. Access is difficult and the site is not well known, but it is possibly the best example of the marl lake habitat in Ireland. In the absence of nutrient data, the site could not be included in the data analysis in the main report.

14 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Ballyeighter Lough 2 (south-west) showing positions of 2012 transects and relevés with depth.

Ballyeighter Lough 2, 2012; Left: Water Clarity looking from the C. curta zone down to the C. rudis- Nuphar lutea band. Right: Chara curta and C. aculeolata.

15 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Bane, 2018 Name Bane Alternative name(s) >16 m based on bathymetric Grid Reference 254766271293, N5476671293 Depth (m) survey in 2007 (Roden 2008) County Meath, Westmeath EPA code 07_270 Area (ha) 75.4 ha OSi 1:50,000 sheet 42 Maximum length 2 km Nutrient data EPA, 1992-2015 (km) Altitude (m) 112 m 002120, Lough Bane and Lough Carboniferous limestone and SAC Geology Glass SAC Chert Previous survey Roden (2008, 2009, 2010), EPA WFD Monitoring Lake Noteworthy species Chara denudata Roden (2008, 2009, 2010) 2018 4, 5, 10, 11, 12, 13 & 14/09/2007 and 2 Snorkel survey date(s) & 3/10/2007, 17/09/2008, 19/06/2009, 02/08/2018 31/08/2010, 01/09/2010 CR, Klaus van de Wyer, John Surveyors CR, PM, JR Bruinsma, Geoff Oliver Number of transects 11 3 Number of relevés 82 20 Secchi depth (m) 5.8 7 m Substrates Marl rock mud Marl, rock mud Noteworthy species Chara denudata Chara denudata A) Vegetation zones 5 5 B) Euphotic depth (m) 9 m T1: 8.5 m; T2: 8.8 m C) C&K score 0.642 T1: 0.7; T2: 0.73 D) Total phosphorus (mg/l) 0.011 0.006 mg/l E) Colour (Hazen units) 11.8 4.23 F) Index (TP × Colour) 0.13 0.025 CONSERVATION GOOD GOOD CONDITION

Hydrochemical data

Water quality data for the period 2008 to 2015 were made available by the EPA, for many samples from multiple depths. Values presented and used in assessment are averages of all data.

Parameter Unit Lough Bane pH 8.1 Alkalinity mg/l 131 Colour Hazen units 4.23 Ammonia mg/l 0.026 Total phosphorus mg/l 0.006 Chlorophyll a µg/l 3.77

Previous survey

The lake vegetation was mapped by Roden (2008) and two transects were re-sampled in 2008, 2009 and 2010. The EPA surveyed the lakes in 2007, 2010 and 2013. Roden (2009) measured nutrients on a monthly basis for one year (15/07/2008-19/06/2009).

Noteworthy species recorded in 2018

Chara denudata occurs as well as several moss species around an underwater spring (Amblystgium riparium, Straminergon (Calliergon) stramineum, Calliergon giganteum, Brachythecium rivulare and Fontinalis

16 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III antipyretica) were noted in 2018. In 2010, Oxrrynchium speciosum and Drepanocladus aduncus were noted from the same station.

Taxa recorded in 2018

Charophytes Vascular plants Other Chara aculeolata Elodea canadensis Fontinalis antipyretica Chara contraria Hippuris vulgaris Other bryophytes Chara curta Lemna trisulca Cyanobacterial crust Chara denudata Myriophyllum alterniflorum Ophrydium versatile Chara hispida Myriophyllum spicatum Red cyanophyte Chara rudis Phragmites australis Chara virgata var. annulata Potamogeton gramineus Chara virgata Potamogeton perfoliatus Nitella flexilis Ranunculus sp. Schoenoplectrus lacustris

Vegetation

The lake is dominated by charophytes with a small cyanobacterial crust zone, due to little outcropping rock. Five vegetation zones are present. An unusual feature is the presence of an underwater spring area where bryophytes and Rorippa sp. replace charophytes down to depths of 5 m.

Lough Bane overview map showing positions of 2018 transects and relevés. Transect 1: 855-859; Transect 2: 860-868; 869: survey of an underwater spring.

17 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cyanobacterial crust

Crust indicator values for Lough Bane are all within the Favourable (Good) targets. Crust chlorophyll a, at 40 µg/cm³, is towards the high end of Good, but the crust in this lake was not previously assessed, so there is no previous figure for comparison.

Change since previous survey

No significant changes noted, except complete recovery from lake lowering episode of 10 years previously.

Threats and pressures

The lake is a water source for Oldcastle Co. Meath. There is little evidence of excess nutrients and water colour is very low. No immediate threats have been noted. Some years ago (2006-07), water abstraction lowered lake level critically, but there is no obvious persistent damage as a result of this episode. The values for both total phosphorus and colour were higher in the 2007-10 period, possibly as a result of the excessive water abstraction.

2018 condition assessment

All parameters were assessed as at Good status, therefore the lake as a whole was assessed as in Favourable (Good) conservation condition. At present Bane is the best example of a marl lake in Eastern Ireland.

Parameter Target Lough Bane 2018 Condition Area Stable or increasing Number of vegetation zones 4 or more* 5 Good Euphotic depth (m) >7 8.8 Good Crust cover (%) >70 92 Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 40±1 Good Crust chlorophytes (% frequency, mean ±s.e.) <45 14.7±1.3 Good C&K score >0.6 0.71 Good at or above above Lake level Good cyanobacterial crust cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 0.006 Good Colour (Hazen units) <15 4.23 Good Index (TP × Colour) ≤0.1 0.025 Good Overall assessment Good

18 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Bleach Lough, 2012 Name Bleach Lough Alternative name(s) Grid Reference 144459154653, R4445954653 Depth (m) County Limerick EPA code 24_90 Area (ha) 18 ha OSi 1:50,000 sheet 65 Maximum length (km) 0.8 km Nutrient data EPA Altitude (m) 2 m SAC n/a Geology Drift over limestone Previous survey Reynolds (2013), EPA WFD Monitoring Lake Noteworthy species Six species of charophyte 2012 Snorkel survey date(s) 22/08/2012 Surveyors CR, PD Number of transects 2 Number of relevés 21 Secchi depth (m) 5.8 m Substrates Marl mud Noteworthy species A) Vegetation zones 4 B) Euphotic depth (m) T1: 7.5 m; T2: 7.5 m C) C&K score 0.77 D) Total phosphorus (mg/l) 0.0045 E) Colour (Hazen units) 13 F) Index (TP × Colour) 0.0585 CONSERVATION CONDITION GOOD

2012 condition assessment

Bleach Lough is one of a group of small kettlehole-shaped lakes in drift with unexpectedly high water transparency (see also Brick and Spring Loughs). Secchi and Euphotic depth are high. Cyanobacterial crust is well developed on the few exposed rocks encountered. Charophyte zonation is well developed and extends to 7.5 m, with C. virgata and C. contraria at station 480. However, the base of the second transect had C. rudis at the unusual depth of 7 m (station 488). Angiosperms are few and typical of marl lakes in good condition (Nuphar lutea, Myriophyllum spicatum, Hippuris vulgaris and Potamogeton perfoliatus). A very interesting feature is the presence of the Zebra Mussel, as in the case of Lough Lene the animal’s population is low and banks of mussels were not seen. The lake’s status is rated Good and an active angling club endeavours to protect water quality.

Bleach Lough 2012; Chara rudis and Potamogeton perfoliatus at 7 m near station 488 at the limit of the euphotic zone.

19 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Bleach Lough showing positions of 2012 transects and relevés with depth.

Bleach Lough from the east.

20 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Brick Lough, 2012 Name Brick Lough Alternative name(s) Grid Reference 163540213918, M6354013918 Depth (m) County Galway EPA code 25_122 Area (ha) c. 1.9 ha OSi 1:50,000 sheet 52 Maximum length (km) 0.2 km Nutrient data None available Altitude (m) 85 m SAC n/a Geology Drift over limestone Previous survey Noteworthy species 2012 Snorkel survey date(s) 05/08/2012 Surveyors CR Number of transects 2 Number of relevés 14 Secchi depth (m) Substrates Grey silt Noteworthy species A) Vegetation zones B) Euphotic depth (m) T2: 6.8 m; T1: 8.4 m C) C&K score 0.21 D) Total phosphorus (mg/l) E) Colour (Hazen units) F) Index (TP × Colour) CONSERVATION CONDITION GOOD

2012 condition assessment

Brick Lough resembles Spring and Bleach Loughs in its kettle-hole shape, with very steep sides dropping to >8 m. It is the smallest water body examined in the survey. There are no surface inflowing streams, it is likely the pond is fed by ground-water. The water is very clear and a strong thermocline was present. Euphotic depth is over 8 m. Cyanobacterial crust was well developed on a single boulder, but hard surfaces were very rare. Charophyte diversity is low with only C. rudis and C. virgata. Equally submerged angiosperms only included Hippuris vulgaris and Potamogeton lucens, although a fringe of floating plants included Oenanthe aquatica, Potamogeton natans and Persicaria amphibia. The moss Fontinalis antipyretica was abundant at depth. The C&K score is very low while the euphotic depth is high. While there is no evidence of eutrophication, Brick Lough is not a typical marl lake. A possible reason is that it is fed by ground-water, which is carbon dioxide-rich, that is not exposed to the surface due to the strong thermocline, in turn a consequence of the lake’s small size and comparatively great depth. This would retard charophyte growth. The lake is classified Good but is a marginal example of a hard water lake.

Brick Lough 2012; Potamogeton lucens at 6.5 m.

21 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Brick Lough showing positions of 2012 transects and relevés with depth.

Brick Lough 2012; Potamogeton natans on the surface along the east edge.

22 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Bunny, 2011 and 2018 Name Lough Bunny Alternative name(s) Grid Reference 137491196757, R3749196757 Depth (m) 15 m County Clare EPA code 27_114 Area (ha) 102.9 ha OSi 1:50,000 sheet 52 Maximum length (km) 2.5 km Nutrient data EPA, 2008-2015 Altitude (m) 17 m 001926, East Burren Complex Carboniferous peloidal SAC Geology SAC limestone and chert August 1981 (Heuff, 1984), Roden (2001), Roden & Murphy (2013); Langangen Previous survey (2005), Pybus et al. (2003), EPA WFD Monitoring Lake Noteworthy species 2011 2018 Snorkel survey date(s) 29/06/2011, 01/07/2011, 24/09/2011 22/09/18 Surveyors CR, PM CR, PM Number of transects 5 2 Number of relevés 41 16 Secchi depth (m) 5-6 m 10 m Substrates Marl, rock, silt, peat Marl rock Potamogeton praelongus and Potamogeton praelongus and Noteworthy species charophytes charophytes A) Vegetation zones 5 5 B) Euphotic depth (m) 8.4 m T1: 7.1 m; T2: 7.1 m C) C&K score 0.59 T1:0.61; T2: 0.64 <0.013 mg/l (see Roden & Murphy, D) Total phosphorus (mg/l) 0.005 mg/l 2013) E) Colour (Hazen units) 8.5 10.6 F) Index (TP × Colour) 0.053 CONSERVATION GOOD GOOD CONDITION

2011 SURVEY

2011 condition assessment

The full report of the 2011 survey of Lough Bunny can be found in Roden & Murphy (2013), when it was assessed as in Good condition. Roden & Murphy (2013) noted possible indications of increasing chlorophyll a. Their total phosphorus values were based on EPA data from 2010/11, when none of the seven measurements was below 0.01 mg/l were measured, leading to an apparent overestimate of the real value.

2018 SURVEY

Hydrochemical data

Water quality data for the period 2008 to 2015 were made available by the EPA, for many samples from multiple depths. Values presented and used in assessment are averages of all data.

Parameter Unit Lough Bunny pH 8.0 Alkalinity mg/l 154 Colour Hazen units 10.6 Ammonia mg/l 0.018 Total phosphorus mg/l 0.006 Chlorophyll a µg/l 1.44

23 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Previous survey

The lake is described in Roden & Murphy (2013) and a preliminary description is given in Roden (2001). The lake is a WFD monitoring lake and, therefore, surveyed by the EPA every three years. Pybus et al. (2003) give an earlier description of the lake’s ecology, while Ryan and Heuff surveyed the lake in 1977 (Heuff, 1984). All surveys recorded a vegetation of charophytes.

Noteworthy species recorded in 2018

Potamogeton praelongus is scarce in Co. Clare.

Taxa recorded in 2018

Charophytes Vascular plants Other Chara virgata var. annulata Hippuris vulgaris Cyanobacterial crust Chara contraria Juncus articulatus Chara curta Littorella uniflora Chara rudis Nuphar lutea Chara virgata Potamogeton gramineus Nitella flexilis Potamogeton perfoliatus Potamogeton praelongus Ranunculus sp. Schoenoplectrus lacustris Utricularia vulgaris/australis

Vegetation

The lake has two main basins separated by a narrow shallow saddle. Cyanobacterial crust and four charophyte zones are present, while Nuphar lutea and Hippuris vulgaris occur above the C. rudis zone.

Cyanobacterial crust

Crust indicator values for Lough Bunny are all within the Favourable (Good) targets, with a particularly low value for chlorophyte abundance. Lough Bunny is considered to be in Favourable (Good) condition.

Change since previous survey

No significant changes have been recorded since the survey in 2001.

Threats and pressures

While Lough Bunny is in Good conservation condition, improved grassland borders the lake to the south-west and north-east. As the lake is ground-water fed, excess fertiliser use or leaky septic tanks at some distance from the lake might threaten the lake’s future. The lake is within the Burren National Park.

24 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Bunny overview map showing positions of 2018 transects and relevés. Transect 1: 131-139; Transect 2: 140-145.

25 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

2018 condition assessment

All parameters were assessed as Good, therefore the lake as a whole was assessed as in Favourable (Good) conservation condition.

Parameter Target Lough Bunny 2018 Condition Area Stable or increasing Stable Number of vegetation zones 4 or more* 5 Good Euphotic depth (m) >7 7.1 Good Crust cover (%) >70 94 Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 22 (4) Good Crust chlorophytes (% frequency, mean ±s.e.) <45 5.0 (2.6) Good C&K score >0.6 0.64 Good at or above Lake level Good cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 0.005 Good Colour (Hazen units) <15 10.6 Good Index (TP × Colour) <0.1 0.53 Good Overall assessment Good

26 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Carra, 2011 and 2018 Name Lough Carra Alternative name(s) Grid Reference 117662272566, M1766272566 Depth (m) >20 m County Mayo EPA code 30_347 Area (ha) c. 1,5464 ha OSi 1:50,000 sheet 38 Maximum length 10 km Nutrient data EPA, 2008-2015 (km) Altitude (m) 18 m Carboniferous limestone, 001774, Lough Carra Mask SAC Geology shale, dark limestone, peloidal Complex SAC limestone, nodular calcarenite August 1977 (Heuff, 1984), King and Champ (1996), Roden & Murphy (2013), EPA Previous survey WFD Monitoring Lake Noteworthy species 2011 2018 13, 16, 20, 21 & 27/07/2011; 03, 04 & Snorkel survey date(s) 09&10/08/2018 11/08/2011, 29/09/2011 Surveyors CR, PM CR, PM, JR Number of transects 27 6 Number of relevés 241 36 3-4 m (Twin Island’s Basin), 4 m Secchi depth (m) (Northern Basin), 5 m (Castlecarra 5.5 m (south of Twin Islands) Basin) Marl, some rock, boulder, silt, sand Substrates Marl, rock and gravel Chara tomentosa, Chara denudata, Noteworthy species Chara denudata, Chara tomentosa Myriophyllum verticilliatum A) Vegetation zones 5 5 T1: 8.6 m (Castlecarra); T2: 4.6 m 9 m (Castlecarra); 4.6 m (Gallagh); (Gallagh); T3: 8 m (Northern); T4: B) Euphotic depth (m) 8 m (Northern); 6.7 m (Twin Island); 5.4 m (Twin Island); T5: 7 m 7 m (Cloonkerry) (Cloonkerry) 0.82 (Castlecarra); 0.92 (Gallagh); 0.79 T1: 0.63; T2: 0.68; T3: 0.52; T4: 0.57; T5: C) C&K score (Northern); 0.56 (Twin Island); 0.87 0.99 (Cloonkerry). D) Total phosphorus (mg/l) 0.009 - 0.01 0.007 E) Colour (Hazen units) 5 - 63 12.25 F) Index (TP × Colour) 0.086 CONSERVATION POOR POOR CONDITION

2011 SURVEY

2011 condition assessment

The full report of the 2011 survey of Lough Carra can be found in Roden & Murphy (2013). The Castle Carra or central basin of Lough Carra was assessed as in Good condition, however the other two Twin Islands and Northern basins showed clear signs of deterioration. These findings were in keeping with those of Hobbs et al. (2005), who showed that sediment phosphorus is increasing in Lough Carra and noted that the increase was greatest in the northern basin and least in the central basin. Roden & Murphy (2013) concluded that Lough Carra was under considerable ecological stress and the assumption that it is Ireland’s best example of a marl lake may cease to be true in the near future.

27 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

2018 SURVEY

Hydrochemical data

Water quality data for the period 2008 to 2015 were made available by the EPA, for many samples from multiple depths. Values presented and used in assessment are averages of all data.

Parameter Unit Lough Carra pH 8.1 Alkalinity mg/l 143 Colour Hazen units 12.25 Ammonia mg/l 0.22 Total phosphorus mg/l 0.007 Chlorophyll a µg/l 3.08 Secchi m 5.5

Previous survey

Several previous accounts contain good data on the benthic macrophytes of Lough Carra. In 1906, Praeger spent several days with a boat exploring the lake and its surroundings (Praeger, 1906). He noted very clear water, a few starved plants and deeper vegetation of Chara hispida/rudis, Potamogeton perfoliatus and Potamogeton nitens. He did not mention Chara tomentosa.

Heuff (1984) reported clear water in Lough Carra when surveyed in 1977 (Secchi of 6.5 m versus 5.0 m in 2011), with Chara curta and Chara contraria descending to 7 m near the Twin Islands. There is no mention of Chara tomentosa, even though the species is abundant in this area in 2011. In 2011, the limit of vegetation off the Twin Islands was at 6 m and Chara rudis and Elodea canadensis were at the base of the euphotic zone (WP 464- 471). This shift in depth and species composition suggests a decreasing light intensity.

In 1996, a detailed grapnel survey of the benthic macrophytes was undertaken by King & Champ (2000). They recorded most of the species and communities noted in 2011 and 2018, with the exception of the river mouth Chara hispida/Chara vulgaris vegetation. They recorded Chara tomentosa for the first time in the lake including near the Twin Islands and part of the western shore of Moorehall Bay. However, they did not report the species from the Castle Island transect nor from other places shown in the vegetation map of Roden & Murphy (2013).

Noteworthy species recorded in 2018

Chara denudata and Chara tomentosa are rare species, although the latter was probably introduced into the lake-or could be expanding due to nutrient increase.

Taxa recorded recorded in 2018

Charophytes Vascular plants Vascular plants Other Chara aculeolata Elodea canadensis Sparganium minimum Callergon giganteum Chara contraria Lemna trisulca Utricularia vulgaris Fontinalis antipyretica Chara curta Myriophyllum alterniflorum Utricularia intermedia Scorpidium scorpioides Chara denudata Myriophyllum verticilliatum Cyanobacterial crust Chara hispida Nuphar lutea Red cyanophyte Chara rudis Phragmites australis Ophrydium versatile Chara tomentosa Potamogeton filiformis Chara virgata Potamogeton gramineus Chara virgata var. annulata Potamogeton lucens Potamogeton perfoliatus Schoenoplectrus lacustris

28 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Vegetation

The lake vegetation was mapped in 2011 (Roden & Murphy, 2013) and little change was detected in this 2018 survey. The grossly eutrophicated area at the mouth of the Annie’s River is still present with a flora very different from the rest of the lake. Species recorded in 2018 included Sparganium emersum, Oenanthe fluviatilis, Lemna trisulca, Ceratophyllum demersum, Elodea canadensis, along with very dense stands of Schoenoplectus lacustris. While such an assemblage might be typical of many lowland lakes and ponds, it contrasts strongly with normal species poor cyanobacterial crust and charophyte-dominated vegetation found in typical marl lakes.

Large stands of Myriophyllum verticillatum occur in the Twin Islands basin growing in depths of 4 to 5 m yet forming visible mats on the surface. A new stand not noted in 2011 is located at M1783570390.

Lough Carra overview map showing positions of 2018 transects and relevés. Transect 1: 5-13; Transect 2: 15-15.3; Transect 3: 16-20; Transect 4: 27-33; Transect 5: 34-42; relevé 14: spot measurement of euphotic depth.

29 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cyanobacterial crust

Lough Carra is a complex, multi-basin lake and research has shown that different nutrient states exist in different basins within the lake, and that these are reflected in the crust metrics (Doddy et al., 2019b). For the present study, two stations were sampled, however, it is recommended that additional stations be included if crust indicators are to be used on an ongoing basis for this lake. The mean figures indicated that, overall, Lough Carra falls into the Favourable (Good) category. Nonetheless, some areas of this lake are in serious decline, and it requires careful monitoring and management.

Change since previous survey

The central Castle Carra basin (T1) remains in Good condition. The Twin Island Basin (T4) showed clear signs of deterioration with a C&K score of 0.57 and euphotic depth of 5.4 m. New patches of Myriophyllum verticillatum have also appeared in the Twin Islands basin. Angiosperms appear to be increasing in the northern basin (declining C&K score). No other significant changes have been recorded since the survey in 2011. The Gallagh basin has not changed since 2011. The most southern or Cloonkerry basin remains in Good condition. A new population of Chara denudata has been recorded in the southern basin.

Threats and pressures

Lough Carra continues to show signs of serious eutrophication, possibly due to more intensive agriculture in the catchment.

2018 condition assessment

As several basins are rated Unfavourable-Inadequate (Poor) (due to decline in euphotic depth, increase in vascular plants and absence of deep charophyte layers) and the Annie’s river area is rated Unfavourable- Bad (due to poor cyanobacterial crust and absence of typical marl lake vegetation), the entire lake is rated Unfavourable-Inadequate (Poor). Nevertheless some parts remain in Good condition and the crust analysis confirms this picture. It is an open question how long these areas will remain in Good condition.

30 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Castlecarra Gallagh Basin Northern Twin Island’s Cloonkerry Parameter Target Lough Carra OVERALL 2018 Basin 2018 2018 Basin 2018 Basin 2018 Basin 2018 Stable or Area Yes Good increasing Number of vegetation zones 4 or more* 5 Good 4 Good 3 Poor 3 Poor Euphotic depth (m) >7 8.6 Good 4.6 Poor 8.0 Good 5.4 Poor 7.0 Good 4.6 Poor Crust cover (%) >70 93% Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 33 µg/cm3 (±5) Good Crust chlorophytes (% frequency, <45 21.47% (±4.7) Good mean ±s.e.) C&K score >0.6 0.63 Good 0.68 Good 0.52 Poor 0.57 Poor 0.99 Good 0.52 Poor at or above Lake level cyanobacterial Yes Good crust Total phosphorus (TP) (mg/l) ≤0.01 0.007 Good Colour (Hazen units) <15 12.25 Good Index (TP × Colour) <0.1 0.086 Good Overall assessment Good Poor Poor Poor Good Poor

31 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cooloorta/ Travaun Lough, 2012 and 2018 Name Cooloorta Lough(Turlough)/ Travaun Lough Alternative name(s) Grid Reference 135334196517, R3533496517 Depth (m) >11 m County Clare EPA code 27_80 Area (ha) 27.9 ha OSi 1:50,000 sheet 52 Maximum length (km) 2.2 km Nutrient data 2 samples collected in 2018 Altitude (m) 16 m 001926, East Burren Complex Carboniferous massive SAC Geology SAC bedded Limestone Previous survey Roden (2000) Noteworthy species 2012 2018 Snorkel survey date(s) 08/08/2012 04/07/2018 Surveyors CR, PM CR, PM Number of transects 2 2 Number of relevés 17 12 Secchi depth (m) 9 m Substrates Marl Marl, rock Noteworthy species Potamogeton praelongus A) Vegetation zones 4 4 B) Euphotic depth (m) >9 m, vegetation on flat bottom at 9 m T1: 7.5 m; T2: 7.5 m; spot check: 8.0 m C) C&K score 0.689 T1: 0.93; T2: 0.87 D) Total phosphorus (mg/l) 0.003 E) Colour (Hazen units) 9.7 F) Index (TP × Colour) 0.029 CONSERVATION GOOD GOOD CONDITION

2012 SURVEY

2012 condition assessment

Perhaps the most transparent lake in the 2012 survey. The lake bottom is at 9 m and Chara contraria was still abundant at this depth. The Chara rudis band is reduced and C. contraria is abundant. Krustenstein is well developed and angiosperms are very sparse, mainly Potamogeton spp. and Juncus bulbosus. There are no obvious threats and the lake is in the Burren National Park. Rated as Good

Cooloorta Lough, 2012; on the marl slope at 6 m, Chara contraria in foreground and Potamogeton praelongus in background.

32 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cooloorta Lough showing positions of 2012 transects and relevés with depth.

Cooloorta Lough, 2012.

33 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

2018 SURVEY

Hydrochemical data

Water quality data are based on two samples taken in 2018

Parameter Unit Cooloorta Lough pH 8.1 Alkalinity mg/l 205 Colour Hazen units 9.7 Ammonia mg/l 0.13 Total phosphorus mg/l 0.003 Chlorophyll a µg/l 0.9 Secchi m 9

Previous survey

The lake vegetation was described by C. Roden in July 2000 (Roden, 2000). The vegetation was again examined by C. Roden and P. Murphy in 2012. P. Doddy took cyanobacterial crust samples in 2016, as well as nutrient samples. No changes in vegetation are noticeable over this period.

Perhaps the most transparent lake in the survey, the lake bottom is at 9 m and Chara contraria was still abundant at this depth. The Chara rudis band is reduced and C. contraria is abundant. Cyanobacterial crust is well developed and angiosperms are very sparse, mainly Potamogeton spp. and Juncus bulbosus.

Noteworthy species recorded in 2018

Potamogeton praelongus is rarely recorded in Co. Clare.

Taxa recorded in 2018

Charophytes Vascular plants Chara aculeolata Potamogeton gramineus Chara curta Potamogeton perfoliatus Chara rudis Potamogeton praelongus Chara virgata Utricularia vulgaris/australis

Vegetation

A small, deep, clear water lake with three separate charophyte zones and cyanobacterial crust. Vascular plants are confined to three species of Potamogeton and Urticularia vulgaris/australis. This low species number probably reflects small size, isolation and very low nutrient levels. Euphotic depth was 7.5 m on Transects 1 and 2, and 8 m adjacent to relevé 734.

Cyanobacterial crust

Cooloorta could not be sampled in 2018 owing to low water levels drying the crust. Doddy et al. (2019) give data for 2016 as follows

 Coverage 100%

 Chlorophyll 18 µg/cm3

 Chlorophytes 8%

These figures place Cooloorta in the Favourable (Good) category.

34 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cooloorta Lough overview map showing positions of 2018 transects and relevés. Transect 1: 732-732.4; Transect 2: 733-733.5.

Change since previous survey

No significant changes note since 2012. Water levels were very low during 2018 sampling, which may have reduced the euphotic depth.

Threats and pressures

There are no obvious threats and the lake is in the Burren National Park.

2018 condition assessment

All metrics were assessed as Good, therefore the lake is assessed as in Favourable (Good) conservation condition.

Cooloorta Lough Parameter Target Condition 2018 Area Stable or increasing Number of vegetation zones 4 or more* 4 Good Euphotic depth (m) >7 7.5, 8.0 Good Crust cover (%) >70 100 Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 18 Good Crust chlorophytes (% frequency, mean ±s.e.) <45 8 Good C&K score >0.6 0.93 Good at or above Lake level at crust level Good cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 0.003 Good Colour (Hazen units) <15 9.7 Good Index (TP × Colour) <0.1 0.029 Good Overall assessment Good

35 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Corrib, 2012 Name Lough Corrib Alternative name(s) Grid Reference 126698236252, M2669836252 Depth (m) County Galway/Mayo EPA code 30_84/ 30_666a, 30_66b Area (ha) c. 16,000 ha OSi 1:50,000 sheet 45 & 38 Maximum length (km) c. 30 km Nutrient data EPA Altitude (m) 4 m SAC 000297, Lough Corrib SAC Geology Limestone and metamorphic Previous survey August 1977 (Heuff, 1984), Roden (2004), EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 02/08/2012 Surveyors CR, PM Number of transects 2 Number of relevés 18 Secchi depth (m) 4.0 m Substrates Marl sand Noteworthy species Chara denudata A) Vegetation zones 5 B) Euphotic depth (m) T1: 5.0 m; T2: 5.0 m C) C&K score 0.94 D) Total phosphorus (mg/l) 0.009 E) Colour (Hazen units) 20.9 F) Index (TP × Colour) 0.18 CONSERVATION CONDITION POOR

2012 condition assessment

Lough Corrib is a very large lake, so the validity of an assessment based on two transects might be questioned. As well as this survey, C. Roden also surveyed the northern arm of Lough Corrib for Galway County Council in August 2012 and found broadly similar conditions. In addition, he examined two transects at Kilbeg pier, about 5 km north of the present transects, in 2004. Data from all of these surveys was considered.

Water colour was dark and Secchi and euphotic depth low. In the northern arm, Secchi was lower again at 2-3 m, as was the euphotic zone. Cyanobacterial crust was either absent or flaking-off limestone boulders and being replaced by Zebra Mussels. Charophyte zonation was intact with C. curta, C. rudis, C. virgata and C. denudata zones present; however the euphotic depth was very shallow. Very few angiosperms were encountered, but the introduced Lagarosiphon major was widespread in the north of the lake. Some charophytes appeared to be dead or dying (see photo below).

In 2004, C. Roden found the euphotic zone extended to 6 m, charophyte zones included C. curta, C. rudis, C. virgata/globularis, C. denudata, C. contraria and Nitella flexilis. In addition, the cyanobacterial crust was in good conditions and Zebra Mussels absent.

The evidence indicates that the lake’s sub-littoral vegetation is declining. In 2012, Lough Corrib was provisionally assessed as Bad, but when the data were re-examined here and the methods of Roden et al. (2020) applied, it was re-assessed as Poor, in particular owing to the continued presence of C. denudata.

Significant further work is required to determine the distribution and conservation condition of lake habitats in Lough Corrib. Corrib, with Mask, is one of the most complex and important lake in the British Isles having base-poor, oligotrophic waters at the north-western end and highly calcareous waters in the southern basin. Habitat 3110 occurs in the north, habitat 3140 on limestone to the south, and it is assumed that a Najas-type lake (3130) should, naturally, occur somewhere in the mix zone between. This is supported by a record for Najas flexilis in Corrib in 1986 (Krause & King, 1994). It follows,

36 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III therefore, that three different condition assessment methods need to be applied. A key question is the number and distribution of transects required to reliably assess the condition of each of the habitats in Lough Corrib.

Lough Corrib showing positions of 2012 transects and relevés with depth.

Lough Corrib 2012; Left: Zebra Mussel and green algae replacing cyanobacterial crust; Right: decaying charophyte lifted from lake floor at 3 m.

37 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cullaun Lough, 2012 Name Lough Cullaun Alternative name(s) Grid Reference 131562190586, R3156290586 Depth (m) County Clare EPA code 27_115 Area (ha) 49.7 ha OSi 1:50,000 sheet 51 Maximum length (km) 1.6 km Nutrient data EPA Altitude (m) 16 m 001926, East Burren Complex SAC Geology Limestone SAC Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 19/07/2012 Surveyors CR, PM Number of transects 2 Number of relevés 12 Secchi depth (m) 4 m Substrates Marl Noteworthy species A) Vegetation zones 4 B) Euphotic depth (m) T1: 5.7 m; T2: 6.0 m, C) C&K score 0.63 D) Total phosphorus (mg/l) 0.0065 E) Colour (Hazen units) 16.5 F) Index (TP × Colour) 0.107 CONSERVATION CONDITION POOR

2012 condition assessment

Lough Cullaun lies close to the Ballyeighter lakes but has a shallower euphotic zone, possibly due to peat staining. Secchi depth is intermediate, but visibility is good underwater. The lake shelves very steeply on its north and south shores but slopes more gently at the east end.

Three charophyte zones occur C. curta, C. rudis and, on the first transect, C. virgata but only to 5.0 m. Cyanobacterial crust is well developed in shallow water.

Cullaun is one of a number of lakes without obvious evidence of habitat degradation, but lacking the deep water communities of the best marl lakes probably due to peat staining of the water reducing the euphotic depth. Some metrics (Colour, index, euphotic depth) just fail to reach the Good standard and the lake is rated borderline Poor, largely on account of the poor or absent deep water vegetation.

Lough Cullaun 2012; Potamogeton x zizii growing amongst C. curta at station 026.

38 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Cullaun showing positions of 2012 transects and relevés with depth.

Lough Cullaun 2012; looking south-west.

39 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cullaunyheeda, 2012 Name Cullaunyheeda Alternative name(s) Grid Reference 148435174671, R4843574671 Depth (m) County Clare EPA code 27_128 Area (ha) 154.8 ha OSi 1:50,000 sheet 58 Maximum length (km) 2 km Nutrient data EPA Altitude (m) 27 m SAC n/a Geology Drift over limestone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 26/07/2012 Surveyors CR, PM Number of transects 2 Number of relevés 16 Secchi depth (m) 2 m Substrates Chara marl Noteworthy species A) Vegetation zones 2 B) Euphotic depth (m) T1: 4.7 m; T2: 5.6 m C) C&K score 0.2 D) Total phosphorus (mg/l) 0.017 E) Colour (Hazen units) 39.9 F) Index (TP × Colour) 0.68 CONSERVATION CONDITION BAD

2012 condition assessment

Cullaunyheeda lies in a limestone basin, but has a very shallow euphotic zone and Secchi depth. The bottom marl suggests a former widespread distribution of charophytes but these are now confined to part of one transect (stations 362-368). Only Chara rudis and Chara virgata occur and neither grows below 2.3 m. Elodea canadensis and Lemna trisulca occur to 4 m. The Zebra Mussel is abundant. While eroded rock was seen in the shallow sub littoral, no well-developed cyanobacterial crust was noted.

As there is good evidence of the lake formerly supporting charophyte beds (Chara marl) and cyanobacterial crust (eroded rock), the lake is regarded as degraded and is rated Bad. This assessment is confirmed by the index value.

Lough Cullaunyheeda, 2012; mud with Chara fragments brought up from below the euphotic zone.

40 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Cullaunyheeda showing positions of 2012 transects and relevés with depth.

Cullaunyheeda, 2012; Lemna trisulca and Chara virgata growing on Chara marl.

41 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Derravarragh, 2012 Name Derravaragh Alternative name(s) Grid Reference 242373266758, N4237366758 Depth (m) County Westmeath EPA code 26_708 Area (ha) 914.2 ha OSi 1:50,000 sheet 41 Maximum length (km) 9.5 km Nutrient data EPA Altitude (m) 61 m SAC n/a Geology Limestone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 13/09/12 Surveyors CR, PM Number of transects 1 Number of relevés 1/5 Secchi depth (m) 3.0 m Substrates Red silt Noteworthy species A) Vegetation zones 1 B) Euphotic depth (m) 4.0 m C) C&K score D) Total phosphorus (mg/l) 0.017 E) Colour (Hazen units) 32.4 F) Index (TP × Colour) 0.55 CONSERVATION CONDITION BAD

2012 condition assessment

The lake has very shallow euphotic zone and Secchi depth. The euphotic zone is largely occupied by drifting Lemna trisulca, which may drift downwards thus creating an overestimate of the zone’s depth. Zebra Mussel is abundant. Only one charophyte was noted, a single clump of C. vulgaris, a possible sign of lake degradation. Cyanobacterial crust exists in very shallow water but is heavily overgrown by green algae. Given the complete absence of charophyte bands, a very shallow euphotic zone and abundant L. trisulca the lake is rated Bad.

On a short visit to the north of the lake in 2009, C. Roden saw extensive beds of charophytes in 1 m depth, however deposition of peat from the River Inney was a serious problem in that part of the lake.

Lough Derravaragh, 2012; Nuphar leaves heavily overgrown by epiphytic diatoms at 1 m.

42 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Derravaragh showing positions of 2012 transects and relevés with depth.

Lough Derravaragh, 2012; Dominant biota, Zebra Mussel and Lemna trisulca at 2 m.

43 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Ennell, 2012 Name Lough Ennell Alternative name(s) Grid Reference 239879246565, N3987946565 Depth (m) County Westmeath EPA code 25_188 Area (ha) 1,156 ha OSi 1:50,000 sheet 48 Maximum length (km) 7 km Nutrient data EPA Altitude (m) 81 m SAC 000685, Lough Ennell SAC Geology Drift over limestone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 12/09/2012 Surveyors CR, PM Number of transects 2 Number of relevés 25 Secchi depth (m) 5 m Substrates Rock, white marl Noteworthy species Tolypella glomerata, Chara denudata, A) Vegetation zones 4 B) Euphotic depth (m) T1: 4.6 m; T2: 6.1 m C) C&K score 0.89 D) Total phosphorus (mg/l) 0.019 E) Colour (Hazen units) 23.7 F) Index (TP × Colour) 0.45 CONSERVATION CONDITION POOR

2012 condition assessment

Lough Ennel is well known as being one of the first Irish lakes to be damaged by eutrophication, however in 2012 it showed many signs of being in good condition. Secchi depth was high while euphotic depth was intermediate. Many rocks had a good development of cyanobacterial crust not overgrown by green algae. Charophyte diversity was high with bands of Chara curta, C. rudis, C. contraria, C. virgata, C. denudata and Tolypella glomerata. The local C. tomentosa occurred in shallow water. Like Bleach Lough, the Zebra Mussel is present but does not form large banks. While the lake has improved since the 1980s, it is still rated Poor on the basis of small euphotic depth, high total phosphorus and high index value.

Lough Ennell, 2012; Base of euphotic zone at station 558. C. denudata

44 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Ennell showing positions of 2012 transects and relevés with depth

Lough Ennell, 2012; Chara tomentosa with cyanobacterial crust at station 560

45 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Errit Lough, 2012 Name Errit Alternative name(s) Grid Reference 153914285143, M5391485143 Depth (m) County Roscommon EPA code 26_702 Area (ha) 82.9 ha OSi 1:50,000 sheet 32 Maximum length (km) 2.2 km Nutrient data Free et al. (2006) Altitude (m) 83 m SAC 000607, Errit Lough SAC Geology Drift over limestone Previous survey 1978 (Heuff, 1984) Noteworthy species 2012 Snorkel survey date(s) 01/09/2012 Surveyors CR, PM Number of transects 2 Number of relevés 13 Secchi depth (m) 3 m Substrates Marl and peat Noteworthy species A) Vegetation zones 4 B) Euphotic depth (m) T1: 3.0 m; T2: 3.5 m, C) C&K score 0.58 D) Total phosphorus (mg/l) 0.01 E) Colour (Hazen units) 46 F) Index (TP × Colour) 0.46 CONSERVATION CONDITION POOR

2012 condition assessment

Errit has very shallow euphotic zone and Secchi depth. It is bordered in part by bogland, which may cause reduction in water transparency. Charophyte zones are not well developed with only Chara contraria and Chara rudis forming substantial beds. Unusually, Littorella uniflora and Scorpidium sp. largely replace charophytes in shallow water at stations 436-438.1. However, charophytes do not grow below 3.0 m where C. rudis and C. virgata co-occur. Cyanobacterial crust is well developed on rocks in shallow water.

Errit is not a very good example of a marl lake due to the shallow euphotic zone and the small number of charophyte species. However, there is no evidence of eutrophication but strong evidence of highly coloured water. The index is also high. The lake is rated Poor due to the shallow euphotic zone, and the possibility that the lake is impacted from water colour needs further research.

Errit Lough, 2012; cyanobacterial crust and Littorella uniflora and Scorpidium sp. station 438.

46 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Errit Lough showing positions of 2012 transects and relevés with depth.

Errit Lough, 2012; looking towards the western shore.

47 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Fahy Lough, 2012 Name Fahy Alternative name(s) Grid Reference 056814255539, L5681455539 Depth (m) County Galway EPA code 32_528 Area (ha) 19.1 ha OSi 1:50,000 sheet 37 Maximum length (km) 0.7 km Nutrient data None available Altitude (m) 6 m 001309, Omey Island Machair Machair sand SAC Geology SAC over granite Previous survey Roden (1999) Noteworthy species 2012 Snorkel survey date(s) 27/09/2012 Surveyors CR, PD Number of transects 2 Number of relevés 13 Secchi depth (m) 4.5 m Substrates Sand Noteworthy species A) Vegetation zones B) Euphotic depth (m) 4.6 m C) C&K score D) Total phosphorus (mg/l) E) Colour (Hazen units) F) Index (TP × Colour) CONSERVATION CONDITION GOOD

2012 condition assessment

Fahy Lough is an excellent example of a machair lough. It is too shallow (4.6 m) for a base to the euphotic zone to be established, but Secchi depth is intermediate 4.5 m. Charophyte bands include C. aspera/ C. curta, C. rudis and C. globularis, as well as Nitella flexilis in one place. Angiosperms include Potamogeton perfoliatus and P. filiformis and Ranunculus baudottii. Cyanobacterial crust is sparsely developed on granite rocks. There is no evidence of eutrophication. Like Aillebrack and other machair loughs, the shallow depth and possibly more eutrophic water mean that these lakes are somewhat different from marl loughs on limestone. Roden (1999) surveyed Fahy and 13 years later there is little change in vegetation. The lake is rated as in Good condition with no obvious threats.

Fahy Lough, 2012; Chara rudis at 2.0 m, station 625.

48 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Fahy Lough showing positions of 2012 transects and relevés with depth.

Fahy Lough, 2012.

49 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Finn Lough, 2012 Name Finn Lough Alternative name(s) Grid Reference 143245169592, R4324569592 Depth (m) County Clare EPA code 27_127 Area (ha) 74.1 ha OSi 1:50,000 sheet 58 Maximum length (km) 1.6 km Nutrient data Free et al. (2006) Altitude (m) 26 m SAC n/a Geology Limestone Previous survey Noteworthy species 2012 Snorkel survey date(s) 26/07/2012 Surveyors CR, PM Number of transects 2 Number of relevés 19 Secchi depth (m) 2.6 m Substrates Silt and peat Noteworthy species A) Vegetation zones 4 B) Euphotic depth (m) 5.0 m C) C&K score 0.624 D) Total phosphorus (mg/l) 0.0105 E) Colour (Hazen units) 27 F) Index (TP × Colour) 0.28 CONSERVATION CONDITION POOR

2012 condition assessment

Finn Lough is not very deep and the euphotic zone depth all but coincides with lake depth. Secchi depth however is very low at 2.6 m. Cyanobacterial crust is developed in shallow water. While Chara curta and Chara rudis zones exist to a depth of 3.7 m, Ceratophyllum demersum occupies the deeper part of the lake - an indicator of an impacted marl lake. This plant is also typical of eutrophic water. The lake is not a good example of a marl lake on limestone and may be enriched either from ground-water or run-off from a nearby industrial unit. The lake is rated Poor on the assumption that the lake’s eutrophication is due to human influence.

Finn Lough, 2012; Ceratophyllum demersum at 4.0 m. station 344.

50 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Finn Lough showing positions of 2012 transects and relevés with depth.

Finn Lough, 2012; Looking west from Transect 1.

51 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough George, 2018 Name Lough George Lough George is name given on six inch map, however this lake is mislabelled as “Ballyeighter Lough” on the Discovery Series and part of an eastern bay of the lake, now partially cut-off by Cladium swamp, is marked as “Lough George”. There are large issues with the lake boundaries in this area at 1:50,000 scale, with submerged Alternative name(s) marl/cyanobacterial crust, Cladium swamp and reedbeds all mapped as dry land. This has led to errors in the EPA’s WFD datasets, where Lough George is labelled as “Ballyeighter Lough”. The original Lough George, as mapped on 6”, is composed of 5 separated WFD lake segment polygons which more or less represent the deeper basins in what seems to be a contiguous lake/wetland Grid Reference 134268191522, R3426891522 Depth (m) >11 m 27_119, 27_299, 27_294, 27_298, County Clare EPA code 27_297 Area (ha) c. 50 ha OSi 1:50,000 sheet 52 Maximum length (km) 2 km Nutrient data None available Altitude (m) 16 m Carboniferous 001926, East Burren Complex SAC Geology monotonous limestone and SAC dolomite Surveyed on 29/08/1978 by H. Heuff and J. Ryan (Heuff, 1984). Langangen (2005) Previous survey (referred to as “South Ballyeighter Lough (by Teernea)”). No EPA data Noteworthy species 2018 Snorkel survey date(s) 04/07/2018 Surveyors CR, PM Number of transects 4 Number of relevés 29 Secchi depth (m) Substrates Marl rock Noteworthy species Chara tomentosa A) Vegetation zones 4 B) Euphotic depth (m) T1: 3.7 m; T2: 5.5 m; T3: 5.4 m; T4: 5.5 m C) C&K score T1: 0.3; T2: 0.48; T3: 0.78; T4: 0.8 D) Total phosphorus (mg/l) E) Colour (Hazen units) F) Index (TP × Colour) CONSERVATION CONDITION GOOD

Previous survey

Examined by Ryan and Heuff in 1978 (Heuff, 1984). A charophyte vegetation of Chara curta, C. rudis, C. contraria, C. virgata and C. tomentosa was recorded with a euphotic depth of 5 m.

Noteworthy species recorded in 2018

Chara tomentosa is only known from Lough George at present in Co. Clare. It was first recorded before 1985 and not seen again until this survey. It was also recorded from Muckanagh Lough but was not seen there, in this survey.

52 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Taxa recorded in 2018

Charophytes Vascular plants Other Chara aculeolata Nuphar lutea Cyanobacterial crust Chara contraria Phragmites australis Chara curta Potamogeton lucens Chara rudis Potamogeton perfoliatus Chara tomentosa Schoenoplectrus lacustris Chara virgata Utricularia vulgarlis/australis Utricularia intermedia agg.

Vegetation

This long narrow lake has six separate deeps. The more northern are surrounded by fen, while exposed limestone occurs in the south. Cyanobacterial crust, C. curta, C. rudis and C. virgata layers occur but euphotic depth is less than 6 m. This may be an underestimate as lake level was very low due to the dry summer.

Lough George overview map showing positions of 2018 transects and relevés. Transect 1: 735-735.8; Transect 2: 736-736.5; Transect 3: 737-737.6.

53 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cyanobacterial crust

Crust indicator values for Lough George are all within the Favourable (Good) targets, with low values for chlorophytes and chlorophyll a, and a value of 100% for crust cover.

Change since previous survey

Apparently little change since 1978, with the rare C. tomentosa still present and no change in euphotic depth.

Threats and pressures

The lake is used by a small group water scheme. A few shore side fields are intensively fertilised.

2018 condition assessment

Lough George had four vegetation zones and scored well on all crust indicators, but a euphotic depth of less than 7 m is a potential cause of concern. This may be accounted for by low water levels, which may be natural, or impacted by the abstraction of drinking water. The overall assessment was Favourable (Good) conservation condition but future monitoring is advisable.

Parameter Target Lough George 2018 Condition Area Stable or increasing Number of vegetation zones 4 or more* 4 Good Euphotic depth (m) >7 5.5 m Poor Crust cover (%) >70 100% Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 16 (2) Good Crust chlorophytes (% frequency, mean ±s.e.) <45 4.0 (1.1) Good C&K score >0.6 0.81 Good at or above Lake level cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 n/a Colour (Hazen units) <15 n/a Index (TP × Colour) <0.1 n/a Overall assessment Good

54 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Hackett, 2012 Name Lough Hackett Alternative name(s) Grid Reference 130686249236, M3068649236 Depth (m) County Galway EPA code 30_339 Area (ha) 41.8 ha OSi 1:50,000 sheet 45 Maximum length (km) 0.9 km Nutrient data None available Altitude (m) 27 m SAC n/a Geology Drift over limestone Previous survey Noteworthy species 2012 Snorkel survey date(s) 21/09/2012 Surveyors CR, PM Number of transects 2 Number of relevés 12 Secchi depth (m) 4.8 m Substrates Silt and gravel Noteworthy species A) Vegetation zones B) Euphotic depth (m) T1: 4.8; T2: 4.1 C) C&K score D) Total phosphorus (mg/l) E) Colour (Hazen units) F) Index (TP × Colour) CONSERVATION CONDITION POOR

2012 condition assessment

Lough Hackett is a small shallow lake in farm land east of Lough Corrib. Above 4 m, charophytes cover most of the bottom, but only two species are common, C. curta and C. contraria. Cyanobacterial crust is well developed in shallow water, but the presence of species such as Potamogeton pectinatus and Ceratophyllum demersum and the shallow euphotic depth suggest more eutrophic conditions. Because of the shallow euphotic depth the lake is classed as Poor.

Lough Hackett, 2012; Chara curta in shallow water at station 611.

55 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Hackett showing positions of 2012 transects and relevés with depth.

Lough Hackett, 2012; Hippuris vulgaris growing on the slope at 1.6 m.

56 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Lene, 2012 Name Lough Lene Alternative name(s) Grid Reference 251073268421, N5107368421 Depth (m) County Westmeath EPA code 07_274 Area (ha) 416.3 ha OSi 1:50,000 sheet 41 & 42 Maximum length (km) 4.4 km Nutrient data EPA Altitude (m) 93 m SAC 002121, Lough Lene SAC Geology Drift over limestone Previous survey Roden (2008), EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 13/09/2012 Surveyors CR, PD Number of transects 2 Number of relevés 14 Secchi depth (m) 5 m Substrates Marl sand Noteworthy species A) Vegetation zones 4 B) Euphotic depth (m) T1: 6.0 m; T2: 7.0 m C) C&K score 0.755 D) Total phosphorus (mg/l) 0.011 E) Colour (Hazen units) 20 F) Index (TP × Colour) 0.44 CONSERVATION CONDITION POOR

2012 condition assessment

Lough Lene is a clear water lake with high Secchi and euphotic depth measurements. Cyanobacterial crust is well developed. Charophyte cover is high with C. curta, C. contraria, C. virgata and C. denudata occurring to a depth of 3.5 m on Transect 1, while C. curta and C. rudis extend to 5.4 m on Transect 2. Below the charophytes, Potamogeton perfoliatus and Elodea canadensis extends to 6-7 m. While the lake appears in good condition owing to the deep euphotic zone, the replacement of deep water charophytes by angiosperms indicates some degree of eutrophication. Equally, the index measurement is quite high, indicating poor condition. While, it appears borderline between Good and Poor, it is here assessed as Poor. Of great interest is the presence of the Zebra Mussel in small numbers (see photo) perhaps showing that the animal can only flourish in very eutrophic conditions.

Lough Lene, 2012; Potamogeton perfoliatus, Elodea canadensis and Zebra Mussel at 6 m at station 583.

57 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Lene showing positions of 2012 transects and relevés with depth.

Lough Lene, 2012; looking west.

58 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Mask, 2012 Name Lough Mask Alternative name(s) Grid Reference 110703263710, M1070363710 Depth (m) County Mayo, Galway EPA code 30_665a Area (ha) 7,797 ha OSi 1:50,000 sheet 38 Maximum length (km) 16 km Nutrient data EPA Altitude (m) 17 m 001774, Lough Carra/Mask Limestone and SAC Geology Complex SAC sandstone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 14/08/2012, 17/08/2012 Surveyors CR, PM, JR, ÁOC Number of transects 4 Number of relevés 28 Secchi depth (m) 5.5 m Substrates Sand mud rock Noteworthy species A) Vegetation zones B) Euphotic depth (m) T1 and T2: 5.5 m; T3: 6.5 m C) C&K score D) Total phosphorus (mg/l) E) Colour (Hazen units) F) Index (TP × Colour) CONSERVATION CONDITION BAD

2012 condition assessment

Lough Mask appears to be severely damaged. The euphotic zone is at best 4.0 m, although a few plants of Chara virgata were noted at 6.5 m on transect 3. Even above 4 m large areas of bare ground were encountered, however Secchi depth was high at 5.5 m. The only charophyte present along the transects was C. virgata growing in small clumps rather than extensive beds. C. aspera was seen close to the shore near transect 3. Cyanobacterial crust is absent, even though eroded rock is plentiful suggesting its former presence. Other plants included Elodea canadensis and Potamogeton species. It is difficult to suggest a cause for the almost complete absence of vegetation, especially as Secchi depth is high. Given the present state of the lake it is classified Bad. Vegetation surveys by the EPA since 2012 yield largely similar results.

Lough Mask, 2012; bare ground at 4 m. Station 409.

59 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Mask showing positions of 2012 transects and relevés with depth.

Lough Mask, 2012; bare ground at 6.7 m. Station 469.

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Melmore Lough, 2018 Name Melmore Lough Alternative name(s) Grid Reference 212857443568, C1285743568 Depth (m) County Donegal EPA code 38_199 Area (ha) 3.4 ha OSi 1:50,000 sheet 2 Maximum length (km) 0.4 km Nutrient data None available Altitude (m) 5 m 000194, Tranarossan and Blown sand on SAC Geology Melmore Lough SAC Monzogranite or diorite Previous survey 1989, N.F. Stewart, C.D. Preston and others; Roden (1999) Noteworthy species 2018 Snorkel survey date(s) 21/08/2018 Surveyors CR, PM, JR Number of transects 3 Number of relevés 11 Secchi depth (m) Substrates Sand Noteworthy species Potamogeton x sparganiifolius A) Vegetation zones 1 B) Euphotic depth (m) 3 m C) C&K score None available D) Total phosphorus (mg/l) None available E) Colour (Hazen units) None available F) Index (TP × Colour) None available CONSERVATION BAD CONDITION

Hydrochemical data

No data were available.

Previous survey

Roden (1999) described the lake as follows in 1999:

This small lake at the tip of the Rosguill Peninsula is of great interest. It lies between a flat machair plain and a steep hill of granite. Despite its small size, it is very deep and in places it was not possible to reach the lake bottom by snorkelling. Much of the lake bed consists of steeply shelving sandy mud with occasional rock outcrops. The sand still retains embedded snail shells down to a depth of 10 m. A small sand shelf runs along the north shore while the south and east shores are of steeply shelving rock. At the “elbow” of the lake an area of shallower sandy mud occurs at a depth of 4-6 m. The water of the lake had the highest Cl content in the survey at 120 mg/l. The water is reasonably transparent. A variety of communities occur, including charophytes on the sand shelf, and Potamogeton pectinatus, Myriophyllum communities at greater depths. Below the limit of vegetation in the northern arm of the lake, very large pale cream coloured freshwater sponges are abundant on rock outcrops. The lake has a diverse Potamogeton flora including a hybrid P. x sparganiifolius.

Noteworthy species recorded in 2018

The unusual Potamogeton hybrid still occurs despite many other changes.

61 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Taxa recorded in 1999 and 2018

1999 2018

Charophytes Chara aspera Chara curta Chara curta Chara contraria Chara contraria Chara virgata Vascular Plants Elodea canadensis Littorella uniflora Myriophyllum alterniflorum Myriophyllum spicatum Myriophyllum spicatum Polygonum amphibium Polygonum amphibium Potamogeton crispus Potamogeton crispus Potamogeton filiformis Potamogeton filiformis Potamogeton friesii Potamogeton hybrid Potamogeton hybrid Potamogeton pectinatus Potamogeton pectinatus Ranunculus hederaceus Bryophytes Fontinalis antipyretica

Vegetation

The vegetation has changed greatly since 1999. The vegetation is now dominated by huge stands of Elodea canadensis and Myriophyllum spicatum. Charophytes are reduced in number of species and are very fouled with epiphytes and sediment. In addition, water is now very dark with the euphotic depth now less than 3 m. The deep sponge community was not re-found.

Melmore Lough overview map showing positions of 2018 transects and relevés.

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Cyanobacterial crust

No crust survey has been conducted.

Change since previous survey

It appears an invasion of Elodea canadensis since 1999 has greatly changed the lake’s vegetation. It is not clear why water transparency should also have declined and epiphytes increased, but it is known that Elodea canadensis has also invaded two nearby Najas flexilis lakes (Sessiagh Lough and Port Lough).

Threats and pressures

The invasion by Elodea canadensis has apparently changed the lake’s former habitat, but the darkened water may also indicate eutrophication. However, the lake has a very small coastal catchment and the surrounding machair did not appear to be intensively farmed. It is possible that, in the future, the impact of Elodea will decline and the original vegetation become re-established as has happened in other lakes invaded by the species.

2018 condition assessment

The lake is rated Unfavourable-Bad (Bad) owing to the loss of several interesting species and vegetation types.

Melmore Lough Parameter Target Condition 2018 Area Stable or increasing Number of vegetation zones 4 or more* 1 Bad Euphotic depth (m) >7 3 m Bad crust cover (%) >70 None available Crust chlorophyll a (µg/cm3 ± s.e.) <45 None available Crust chlorophytes (% frequency, mean ±s.e.) <45 None available C&K score >0.6 None available at or above Lake level cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 None available Colour (Hazen units) <15 None available Index (TP × Colour) <0.1 None available Overall assessment Bad

63 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Muckanagh Lough, 2012 and 2018 Name Muckanagh Lough Alternative name(s) Grid Reference 137123192809, R3712392809 Depth (m) >7 m County Clare EPA code 27_94 Area (ha) 96.1 ha OSi 1:50,000 sheet 52 Maximum length (km) 1.7 km Nutrient data EPA, 2008-2015 Altitude (m) 17 m 001926, East Burren Complex Carboniferous crinoidal SAC Geology SAC limestone and chert Previous survey August 1984 (Heuff, 1984), Langangen (2005), EPA WFD Monitoring Lake Noteworthy species 2012 2018 Snorkel survey date(s) 18/07/2012 16/07/2018 Surveyors CR, PM CR, PM Number of transects 2 3 Number of relevés 19 25 Secchi depth (m) 4.3 m 5.1 Substrates Marl peat Marl, rock Noteworthy species Potamogeton praelongus A) Vegetation zones 4 4 B) Euphotic depth (m) 6.5 m T1: 6.1 m; T2: 6.1 m; T3: 5.2 m C) C&K score 0.853 T1:0.60, T2:0.61, T3:0.67 D) Total phosphorus (mg/l) 0.008 0.008 E) Colour (Hazen units) 0.078 25 F) Index (TP × Colour) 0.2 0.2 CONSERVATION GOOD GOOD CONDITION

2012 SURVEY

2012 condition assessment

Muckanagh has coloured water probably due to peat runoff. Secchi and euphotic depth were intermediate. Cyanobacterial crust is extremely well-developed, apparently eroding whole boulders. Charophyte bands include C. curta, C. rudis and C. globularis. Fontinalis appears to occur on the bottom and C. tomentosa has been recorded in the past. Angiosperms are few with the exception of Urticularia intermedia which is abundant reaching cover values of 4 in places. Other than the presumed peat influence the lake is in good condition and is rated Good.

Muckanagh Lough, 2012; abundant Urticularia intermedia.

64 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Muckanagh Lough showing positions of 2012 transects and relevés with depth.

Muckanagh Lough, 2012; Chara curta bed at 2 m. Station 5.

65 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

2018 SURVEY

Hydrochemical data

Water quality data for the period 2008 to 2015 were made available by the EPA, for many samples from multiple depths. Values presented and used in assessment are averages of all data.

Parameter Unit Muckanagh Lough pH 8.2 Alkalinity mg/l 198 Colour Hazen units 25 Ammonia mg/l 0.17 Total phosphorus mg/l 0.008 Chlorophyll a µg/l 3.92 Secchi m 5.1

Previous survey

Examined by Ryan and Heuff in 1977 who recorded a vegetation of charophytes, including the rare Chara tomentosa, but gave no precise details about its location (Heuff, 1984). The lake was sampled by C. Roden and P. Murphy in 2012 (see above). It is a WFD monitoring lake and macrophytes are surveyed by the EPA every three years.

Noteworthy species recorded in 2018

Potamogeton praelongus is scarce in Co. Clare. A pre-1985 record for Chara tomentosa was not confirmed but the plant grows in nearby Lough George which is connected to Muckanagh by a series of pools and fen which probably flood in winter.

Taxa recorded in 2018

Charophytes Vascular plants Other Chara aculeolata Elodea canadensis Cyanobacterial crust Chara contraria Nuphar lutea Red cyanophyte Chara curta Phragmites australis Fontinalis antipyretica Chara rudis Potamogeton lucens Chara virgata Potamogeton perfoliatus Potamogeton praelongus Schoenoplectrus lacustris Utricularia intermedia Utricularia vulgaris

Vegetation

The lake is a large, shallow basin with drainage from nearby fen and cut over bog. The cyanobacterial crust is very well-developed and over 20 cm thick in places. The charophyte zones of Chara curta, C. rudis and C. virgata are present, with vascular plants including Schoenoplectus lacustris and Phragmites australis.

Cyanobacterial crust

The crust indicator values for Muckanagh Lake are all well within the green areas, therefore, Muckanagh is considered to be in Favourable (Good) condition.

Change since previous survey

No significant changes have been recorded since the survey in 2012.

66 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Muckanagh Lough overview map showing positions of 2018 transects and relevés. Transect 1: 757- 765.1; Transect 2: 766-773; Transect 3: 775-779.

Threats and pressures

There are no significant pressures or threats although water colour is high at 25 Hazen units, probably reflecting run off from cut-over bog.

2018 condition assessment

The lake remains in Favourable (Good) conservation condition. Nevertheless colour is high and euphotic depth slightly lower than the 7 m indicative of Good condition. Like other highly coloured but nutrient- poor lakes (e.g. Walshpool), it is possible that the lake is damaged by excess runoff from nearby bog land. Further research on this matter would help clarify the matter. Further searches for Chara tomentosa would also be useful.

Muckanagh Lough Parameter Target Condition 2018 Area Stable or increasing Number of vegetation zones 4 or more* 4 Good Euphotic depth (m) >7 6.1 m Poor Crust cover (%) >70 98 Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 29 (±3) Good Crust chlorophytes (% frequency, mean ±s.e.) <45 23.7 (±3.9) Good C&K score >0.6 0.67 Good at or above Lake level cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 0.008 Good Colour (Hazen units) <15 25 Poor Index (TP × Colour) <0.1 0.2 Poor Overall assessment Good

67 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Owel, 2011 and 2018 Name Lough Owel Alternative name(s) Grid Reference 240322258331, N4032258331 Depth (m) 25 m County Westmeath EPA code 26_703 Area (ha) 1,021.8 ha OSi 1:50,000 sheet 41 Maximum length (km) 6.2 km Nutrient data EPA, 2008-2015 Altitude (m) 97 m Carboniferous limestone and SAC 000688, Lough Owel SAC Geology Chert 1892-1895 Levinge, Bullock Webster, Groves, Linton, Marshall (see Groves & Bullock-Webster, 1920, 1924), 1895 Marshall, 1977 (Heuff, 1984), 1970s and 1981 by Previous survey the Central Fisheries Board (reported in John et al., 1982). EPA WFD Monitoring Lake Noteworthy species 2011 2018 Snorkel survey date(s) 17, 18 & 31/08/2011, 01/09/2011 1/8/2018 Surveyors CR, PM CR, PM, JR Number of transects 16 3 Number of relevés 132 20 Secchi depth (m) 4-5.5 m 6 m Peat, silt, mud, sand, gravel, cobble, Substrates Marl, rock rock, boulder Chara denudata, Chara tomentosa, Noteworthy species Chara denudata, Chara tomentosa Potamogeton filiformis A) Vegetation zones 6 6 B) Euphotic depth (m) 7.0 m T1: 8.0 m; T2: 5.7 m; T3: 6 m C) C&K score 0.794 T1: 0.73; T2: 0.95; T3: 1.0 D) Total phosphorus (mg/l) 0.012 0.01 E) Colour (Hazen units) 8.5 6.85 F) Index (TP × Colour) 0.1 0.0685 CONSERVATION GOOD GOOD CONDITION

2011 SURVEY

2011 condition assessment

The full report of the 2011 survey of Lough Owel can be found in Roden & Murphy (2013). Euphotic depths of 7 m were recorded in Owel in 2011, similar to that found in 1977 (Heuff, 1984). Species recorded in the 1890s by Levinge, Bullock Webster, Groves, Linton and Marshall (see Groves & Bullock- Webster, 1920, 1924) were re-found, including Chara aspera and Chara rudis. Full development of charophyte zones was found and a cyanobacterial crust zone was present. Lough Owel was assessed as in Good conservation condition.

68 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

2018 SURVEY

Hydrochemical data

Water quality data for the period 2008 to 2015 were made available by the EPA, for many samples from multiple depths. Values presented and used in assessment are averages of all data.

Parameter Unit Lough Owel pH 8.4 Alkalinity mg/l 108 Colour Hazen units 6.85 Ammonia mg/l 0.033 Total phosphorus mg/l 0.01 Chlorophyll a µg/l 4.77 Secchi m 6.0

Previous survey

Heuff and Ryan surveyed the lake in 1977, and found charophyte vegetation to a depth of 7 m (Heuff, 1984). Chara contraria occurred at depth, while C. rudis, C. aculeolata and C. tomentosa occurred in shallower water. John et al. (1982) resurveyed the lake in 1980-81 and reported many of the same communities. The lake vegetation was mapped by Roden & Murphy (2013). The EPA surveyed the lake in 2007, 2010 and 2013. All surveys suggested the lake was in Good conservation condition.

Noteworthy species recorded in 2018

Chara denudata, Chara tomentosa and Potamogeton filiformis.

Taxa recorded in 2018

Charophytes Vascular plants Other Chara aspera Elodea canadensis Cyanobacterial crust Chara contraria Littorella uniflora Fontinalis sp. Chara curta Myriophyllum alterniflorum Chara denudata Myriophyllum spicatum Chara rudis Potamogeton filiformis Chara tomentosa Potamogeton friesii Chara virgata Potamogeton gramineus Potamogeton perfoliatus Potamogeton x angustifolius Ranunculus sp

Vegetation

During the survey, the water level was low so that the cyanobacterial crust zone was exposed and dry. The east and south shores shelve rapidly, the western shore has a wider vegetation zone. Chara curta, C. contraria, C.rudis, C. virgata and C. denudatata zones were seen. Euphotic depths measured on T1-T3 had not changed since 2011.

Cyanobacterial crust

Values for Lough Owel fall within the orange ‘Unfavourable-Inadequate’ or ‘Poor’ zone for two of the factors considered (crust cover and chlorophyll concentration). Furthermore, the figure for chlorophyll a, at 46 µg/cm³, is substantially higher than the mean value recorded in 2016 (30 µg/cm³). Lough Owel has a number of underwater springs which deliver water from the catchment into parts of the lake. It was observed during this study that proximity to one of these springs has a strong effect on the phytobenthos; cyanobacterial crust, which is an indication of good conditions, does not grow close

69 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III to the ground-water springs. The photograph below shows two stones, one (right) from beside a spring, another from 5 m away from the spring. Each spring is surrounded by a crust-free zone for at least a few metres in diameter. The long-term effect of this inflowing ground-water in the lake is expected to be negative.

Lough Owel overview map showing positions of 2018 transects and relevés. Transect 1: 841-844; Transect 2: 846-849; Transect 3: 851-854.

70 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Underwater springs, which deliver ground-water from the catchment into Lough Owel, are surrounded by a crust-free zone. The stone on the right, without crust, is from such a spring. The encrusted stone (left), from 5m away from the spring, shows the more typical crust cover.

Change since previous survey

No significant changes noted in the macrophytes since the 2011 surveys.

Threats and pressures

The lake is a water source, both for drinking and supplying the Royal Canal. There is little evidence of excess nutrients (but see discussion on cyanobacterial crusts) and water colour is very low. The absence of crust around ground-water springs does suggest that this water is nutrient enriched.

2018 condition assessment

With the exception of the crust metrics, indicators are assessed as Good. Crust values may reflect ground-water inputs at the location sampled, as ground-water might be nutrient enriched. It is also possible however, that the crust metrics are indicators of forthcoming problems. As crust metrics are a new indicator, further work on sample location may be needed to take account of localised enrichment. Overall, the lake is assessed as in Good conservation condition, with the caveat that the crust data, euphotic depths on two of the three transects and observed water levels indicate the lake may be in decline and, therefore, regular monitoring is essential.

Parameter Target Lough Owel 2018 Condition Area Stable or increasing Number of vegetation zones 4 or more* 6 Good Euphotic depth (m) >7 8.0 Good Crust cover (%) >70 50 Poor Crust chlorophyll a (µg/cm3 ±s.e.) <45 46 (±1) Poor Crust chlorophytes (% frequency, mean ±s.e.) <45 37.7 (±11) Poor C&K score >0.6 1.0 Good at or above Lake level Below Poor cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 0.01 Good Colour (Hazen units) <15 6.85 Good Index (TP × Colour) <0.1 0.0685 Overall assessment GOOD

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Lough Rea, 2012 and 2018 Name Lough Rea Alternative name(s) Loughrea Grid Reference 161538215480, M6153815480 Depth (m) >20 m County Galway EPA code 29_194 Area (ha) 301.1 ha OSi 1:50,000 sheet 52 Maximum length (km) 2.7 km Nutrient data EPA, 2008-2015 Altitude (m) 81 m Carboniferous Waulsortian SAC 000304, Lough Rea SAC Geology limestone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 2018 Snorkel survey date(s) 01/07/2012, 20/07/2012 31/08/2018 Surveyors CR, PM CR, PM, JR Number of transects 2 2 Number of relevés 26 13 Secchi depth (m) 5.2 m 5.5 m Substrates Marl Marl, rock Chara tomentosa, Potamogeton Noteworthy species Chara tomentosa pectinatus A) Vegetation zones 4 4 B) Euphotic depth (m) T1: 11 m; T2: 11 m T1: 8.5 m; T2: 8.5 m C) C&K score 0.93 T1: 0.85; T2: 0.94 D) Total phosphorus (mg/l) 0.008 0.008 mg/l E) Colour (Hazen units) 5.7 5.7 F) Index (TP × Colour) 0.00427 0.0427 CONSERVATION GOOD GOOD CONDITION

2012 SURVEY

2012 condition assessment

Lough Rea has the deepest euphotic zone encountered in the survey, 10-11 m. Secchi is high at 5.2 m. It is an excellent example of a marl lake almost completely dominated by charophytes and cyanobacterial crust with very little angiosperm cover. The C. rudis band is barely present, a possible indicator of a marl lake with very low nutrients. It closely resembles Lough Owel surveyed in 2011 (and 2018), which also supports a population of C. tomentosa. Surprisingly, no C. denudata was encountered but the deep C. contraria had ecorticate branches. Further survey might increase the charophyte species list. Given its deep euphotic zone, charophyte dominance and clear water, it is in Good (very good?) condition. As the town of Loughrea is on the lakeshore this total absence of eutrophication is surprising.

Lough Rea, 2012; Chara contraria at depth (10 m), station 56.

72 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Rea showing positions of 2012 transects and relevés with depth.

Lough Rea, 2012; Chara contraria at 4 m, station 38.

73 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

2018 SURVEY

Hydrochemical data

Water quality data for the period 2008 to 2015 were made available by the EPA, for many samples from multiple depths. Values presented and used in assessment are averages of all data.

Parameter Unit Lough Rea pH 8.1 Alkalinity mg/l 106 Colour Hazen units 5.7 Ammonia mg/l 0.21 Total phosphorus mg/l 0.008 (0.0075) Chlorophyll a µg/l 9.32 Secchi m 5.5

Previous survey

The lake vegetation was examined by C. Roden and P. Murphy in 2012 (see above). The EPA surveyed the lake in 2007, 2010 and 2013. It is a WFD monitoring lake.

Noteworthy species recorded in 2018

Chara tomentosa is rare in the west of Ireland only growing in Lough Rea, Lough George, and Lough Carra where it appears introduced.

Taxa recorded in 2018

Charophytes Vascular plants Other Chara aculeolata Littorella uniflora Cyanobacterial crust Chara contraria Myriophyllum alterniflorum Ophrydium versatile Chara curta Myriophyllum spicatum Chara rudis Potamogeton pectinatus Chara tomentosa Chara virgata var. annulata

Vegetation

Lough Rea is notable for the extensive beds of C. contraria which partially replace Chara rudis.

Cyanobacterial crust

The crust values for Lough Rea are within the targets for Favourable conservation condition, and it is considered to be in Favourable (Good) condition. However with crust chlorophyll of 40 µg/cm³ (up from 28 µg/cm³ in 2016), it is approaching the threshold between Favourable (Good) and Unfavourable- Inadequate (Poor). Crust cover was also measured in 2016, giving a value of 96%. The present figure of 88% may again indicate a slight decrease in quality. This is a lake which needs careful monitoring to see if this indication of decline is part of a longer-term trend.

Change since previous survey

No significant changes were noted between surveys, however euphotic depth, while still excellent, was lower than the extreme value of 11 m recorded in 2012. This partially reflects low water levels in 2018 but it may also reflect variations in the vegetation lower boundary over small distances along the lake bed.

74 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Lough Rea overview map showing positions of 2018 transects and relevés. Transect 1: 93-97; Transect 2: 99-103.

Threats and pressures

The town of Loughrea lies on the north shore of the lake, and the lake is the water supply for the town, but no signs of human impact were detected.

2018 condition assessment

All parameters were assessed as at Good status, therefore the lake as a whole was assessed as in Favourable (Good) conservation condition. However, crust data may indicate slight nutrient enrichment and further monitoring is essential.

Parameter Target Lough Rea 2018 Condition Area Stable or increasing Number of vegetation zones 4 or more* 4 Good Euphotic depth (m) >7 8.5 Good Crust cover (%) >70 88 Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 40 (±3) Good Crust chlorophytes (% frequency, mean ±s.e.) <45 22.7 (±0.4) Good C&K score >0.6 0.94 Good at or above above Lake level Good cyanobacterial crust cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 0.008 Good Colour (Hazen units) <15 5.7 Good Index (TP × Colour) ≤0.1 0.043 Good Overall assessment Good

75 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Spring Lough, 2012 Name Spring Lough Alternative name(s) Grid Reference 286106303952, H8610603952 Depth (m) >9 m County Monaghan EPA code 06_198 Area (ha) 10.3 ha OSi 1:50,000 sheet 35 Maximum length (km) 0.6 km Nutrient data EPA Altitude (m) 28 m SAC n/a Geology Drift over limestone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 07/09/2012 Surveyors CR, PM Number of transects 2 Number of relevés 14 Secchi depth (m) 3.0 m Substrates Marl Noteworthy species A) Vegetation zones 4 B) Euphotic depth (m) T1: 6.7 m; T2: 7.2 m C) C&K score 0.64 D) Total phosphorus (mg/l) 0.014 E) Colour (Hazen units) 25.2 F) Index (TP × Colour) 0.35 CONSERVATION GOOD CONDITION

2012 condition assessment

Spring Lough is a ground-water-fed kettle-hole lake in drift. Euphotic depth is 6-7 m, but Secchi depth is low, perhaps due to a blue-green algal bloom. Restricted Chara curta and C. aculeolata zones occur, but C. rudis forms the only large charophyte zone, while C. virgata occurs at depth along with abundant Fontinalis antipyretica. Angiosperms include Nymphaea alba, Elodea canadensis and Potamogeton species. Cyanobacterial crust is well developed on a few boulders but bed rock is absent. This lake closely resembles Brick Lough. While vegetation structure (number of vegetation zones, C&K score) and euphotic depth are favourable, total phosphorus and colour are somewhat high and the lake is subject to cyanobacterial blooms. Provisionally it is rated Good. Small kettle hole lakes in glacial drift, fed by ground-water may require different assessment than the more typical marl lakes on limestone bedrock. It is used as part of the Carrickmacross water supply but future plans will see less water being abstracted.

Spring Lough, 2012; Chara aculeolata at station 534.

76 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Spring Lough showing positions of 2012 transects and relevés with depth.

Spring Lough, 2012; Fontinalis antipyretica growing at depth, station 547.

77 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Summerhill Lough, 2012 Name Summerhill Lough Alternative name(s) Grid Reference 249066327952, H4906627952 Depth (m) County Monaghan, Fermanagh EPA code 36_721 Area (ha) 2.5 ha OSi 1:50,000 sheet 28A Maximum length (km) 0.25 km Nutrient data EPA Altitude (m) 57 m 001786, Kilroosky Lough SAC Geology Calcareous drift Cluster SAC Previous survey EPA WFD Monitoring Lake Noteworthy species none 2012 Snorkel survey date(s) 07/09/2012 Surveyors CR, PM Number of transects 1 Number of relevés 0 Secchi depth (m) Substrates Dark mud Noteworthy species none A) Vegetation zones 0 B) Euphotic depth (m) 1.5 C) C&K score 0 D) Total phosphorus (mg/l) 0.0245 E) Colour (Hazen units) 46.1 F) Index (TP × Colour) 1.129 CONSERVATION BAD CONDITION

2012 condition assessment

The lake contained no charophytes along the transect examined. The water was dark and total phosphorus high. Apparently in one small area charophytes persist (N. Stewart, pers. com.) Based on the 2012 data the lake is rated Bad.

Summerhill Lough showing position of 2012 transects and relevé with depth.

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Urlaur Lough, 2012 Name Urlaur Lough Alternative name(s) Grid Reference 151141288814, M5114188814 Depth (m) County Mayo EPA code 26_689 Area (ha) 115.7 ha OSi 1:50,000 sheet 32 Maximum length (km) 3 km Nutrient data EPA Altitude (m) 81 m SAC 001571, Urlaur Lakes SAC Geology Drift over limestone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 16/08/2012 Surveyors CR, PM Number of transects 2? Number of relevés 12 Secchi depth (m) 1.5 m Substrates Sand mud Noteworthy species Callitriche hermaphroditica A) Vegetation zones 2-3 B) Euphotic depth (m) T2: 1.4 m; T1: 2.1 m C) C&K score 0.77 D) Total phosphorus (mg/l) 0.012 E) Colour (Hazen units) 41.5 F) Index (TP × Colour) 0.498 CONSERVATION POOR CONDITION

2012 condition assessment

Urlaur Lough has both a shallow euphotic zone and low Secchi depth. Charophyte bands include Chara curta/C. contraria and Chara virgata, extending to about 2 m. Cyanobacterial crust is well developed on occasional boulders. The Swan Mussel is abundant. Callitriche hermaphroditica is an unusual angiosperm. Given the shallow euphotic zone, few charophyte bands with Elodea cannadensis common along the base of the euphotic zone, the lake is rated Poor.

Urlaur Lough, 2012; Chara contraria at station 427.

79 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Urlaur Lough showing positions of 2012 transects and relevés with depth.

Urlaur Lough, 2012; esker extending into the lake.

80 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Walshpool Lough, 2012 Name Walshpool Lough Alternative name(s) ‘Washpool’ (typographic error on 1:50,000 data sets) Grid Reference 121632284137, M2163284137 Depth (m) County Mayo EPA code 34_402 Area (ha) 44.7 ha OSi 1:50,000 sheet 31 Maximum length (km) 1.2 km Nutrient data EPA Altitude (m) 32 m SAC n/a Geology Drift over limestone Previous survey EPA WFD Monitoring Lake Noteworthy species 2012 Snorkel survey date(s) 21/09/2012 Surveyors CR, PM Number of transects 2 Number of relevés 17 Secchi depth (m) 3.8 m Substrates Marl Noteworthy species Potamogeton filiformis A) Vegetation zones 4 B) Euphotic depth (m) 3.3 m, C) C&K score 0.822 D) Total phosphorus (mg/l) 0.0095 E) Colour (Hazen units) 34.8 F) Index (TP × Colour) 0.33 CONSERVATION POOR CONDITION

2012 condition assessment

Walshpool is a lake with large deposits of marl. While the euphotic zone is shallow well-developed charophyte bands occur including Chara curta, C. rudis and C. virgata. Cyanobacterial crust is well- developed. Water clarity is high, but has an obvious yellow hue. There is a wonderful sponge fauna present. Few angiosperms occur other than Potamogeton filiformis. As the euphotic zone is very shallow, conservation condition is problematic to assess. Water colour is high and euphotic depth low, therefore the lake is rated Poor on the assumption that high colour is due to peat drainage.

Walshpool Lough, 2012.

81 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Walshpool Lough showing positions of 2012 transects and relevés with depth.

Walshpool Lough, 2012; Large Sponge at base of Schoenoplectus lacustris.

82 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

White Lough, 2018 Name White Lough Alternative name(s) Annagh Lough Grid Reference 251154273108, N5115473108 Depth (m) County Meath, Westmeath EPA code 07_258 Area (ha) 25.1 ha OSi 1:50,000 sheet 41 Maximum length (km) 1.2 km Nutrient data EPA, 2008-2015 Altitude (m) 106 m 001810, White Lough, Ben Carboniferous Cherty SAC Geology Loughs and Lough Doo SAC Limestone Previous survey Roden (2008), EPA WFD Monitoring Lake Noteworthy species 2007 2018 Snorkel survey date(s) Sep& Oct 2007 31/07/2018 Surveyors CR, CR, PM, JR Number of transects 3 3 Number of relevés 35 21 Secchi depth (m) 9 m Substrates Marl, rock Marl, rock Noteworthy species Potamogeton filiformis Potamogeton filiformis A) Vegetation zones 4 4 B) Euphotic depth (m) 8.1 T1: 6.4 m; T2: 6.4 m; T3: 6.4 m C) C&K score 0.73 0.74, 0.86, 1.0 D) Total phosphorus (mg/l) 0.006 mg/l E) Colour (Hazen units) 12.5 F) Index (TP × Colour) 0.075 CONSERVATION GOOD GOOD CONDITION

Hydrochemical data

Water quality data for the period 2008 to 2015 were made available by the EPA, for many samples from multiple depths. Values presented and used in assessment are averages of all data.

Parameter Unit White Lough pH 8.2 Alkalinity mg/l 191 Colour Hazen units 12.5 Ammonia mg/l 0.033 Total phosphorus mg/l 0.006 Chlorophyll a µg/l 6.59 Secchi m 9.1

Previous survey

The lake vegetation was examined by C. Roden in 2007 (Roden, 2008). He recorded four vegetation zones, a euphotic depth of 8.1 m and calculated a C&K score of 0.73. The EPA surveyed the lakes in 2007, 2010 and 2013 and rated it as Good Ecological Status under the WFD.

Noteworthy species recorded in 2018

Potamogeton filiformis is a pondweed mainly found in the north and west of Ireland.

83 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Taxa recorded in 2018

Charophytes Vascular plants Other Chara aculeolata Elodea canadensis Fontinalis antipyretica Chara contraria Hippuris vulgaris Cyanobacterial crust Chara curta Myriophyllum verticillatum Ophrydium versatile Chara rudis Potamogeton filiformis Chara virgata Potamogeton natans Schoenoplectrus lacustris Utricularia vulgaris/australis

Vegetation

A very small but clear marl lake that has fluctuations in water level. In 2018, levels were too low to find much cyanobacterial crust. An underwater spring was surrounded by Hippuris vulgaris and filamentous algae. Four vegetation zones occur: cyanobacterial crust, Chara curta, C. rudis and, in the north arm, C. virgata.

White Lough overview map showing positions of 2018 transects and relevés. Transect 1: 820-826; Transect 2: 828-834; Transect 3: 835-839; relevés 827-827.2: investigation of an underwater spring.

84 IWM 124 (2020) Benthic vegetation of Irish marl lakes, 2011-2018, Appendix III

Cyanobacterial crust

Due to very low summer water levels in 2018, rocks with crust were too dry to sample from the shore. Therefore no crust data were collected.

Change since previous survey

No significant changes noted since 2007 survey. Very low water levels during sampling did reduce the measured euphotic depth.

Threats and pressures

While the lake appears in very good ecological condition, it is fed by ground-water and its level fluctuates. Intensive farming or increased ground-water use may be a problem in future. The low water level in 2018 was possibly caused by the dry summer of that year. Thus changes in seasonal rainfall due to climate change could become an issue.

2018 condition assessment

All parameters were assessed as Good with the exception of water level, which was marginal Poor, being just above the Chara curta zone, therefore the lake as a whole was assessed as in Favourable (Good) conservation condition. Crust seen at depth appeared to be in good order, but could not be reached from the shore by Dr Doddy and so was not sampled.

Parameter Target White Lough 2018 Condition Area Stable or increasing Number of vegetation zones 4 or more* 4 Good Euphotic depth (m) >7 6.4 Good Crust cover (%) >70 not measured Good Crust chlorophyll a (µg/cm3 ±s.e.) <45 not measured Good Crust chlorophytes (% frequency, mean ±s.e.) <45 not measured Good C&K score >0.6 1.0 Good at or above below Lake level Poor cyanobacterial crust cyanobacterial crust Total phosphorus (TP) (mg/l) ≤0.01 0.006 Good Colour (Hazen units) <15 12.5 Good Index (TP × Colour) <0.1 0.075 Good Overall assessment Good

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